United States v. Castillo

Opinion

United States Court of Appeals For the First Circuit

No. 23-2074

UNITED STATES OF AMERICA,

Appellee,

v.

FERMIN CASTILLO,

Defendant, Appellant.

APPEAL FROM THE UNITED STATES DISTRICT COURT FOR THE DISTRICT OF MASSACHUSETTS

[Hon. William G. Young, U.S. District Judge]

Before

Barron, Chief Judge, Montecalvo and Rikelman, Circuit Judges.

Michael Pabian for appellant.

Mark T. Quinlivan, Assistant United States Attorney, with whom Joshua S. Levy, Acting United States Attorney, was on brief, for appellee.

October 24, 2025 MONTECALVO, Circuit Judge. Defendant-appellant Fermin

Castillo appeals his jury conviction and sentence for drug

distribution and money laundering conspiracy violations. Castillo

helped lead a fentanyl-distribution organization in Boston in 2020

and 2021. Discerning no reversible error among the many claims

raised to us -- challenges to the district court's refusal to

dismiss the indictment before trial; certain evidentiary rulings;

alleged prosecutorial misconduct; aspects of the jury

instructions; and aspects of sentencing -- we affirm.

I. Facts

Because this appeal does not raise a

sufficiency-of-the-evidence challenge, we rehearse the facts "in

a 'balanced' manner." United States v. Martínez-Mercado, 132 F.4th

61, 65 (1st Cir. 2025) (quoting United States v. Lanza-Vázquez,

799 F.3d 134, 138 n.1 (1st Cir. 2015)).

From March 2020 to March 2021, Castillo worked with Cesar

Alejandro Castro Pujols ("Castro") and Andre Heraux Martinez

("Heraux"), among others, to distribute fentanyl in Boston.

Castillo lived in Mexico during this time. His role in the drug

organization was to arrange many of the large drug sales and to

organize the movement of proceeds back to Mexico. Castillo

typically gave instructions to his Boston-based associates,

including Castro and Heraux, over cell phones using WhatsApp.

Although Castillo did not himself typically conduct drug sales or

- 2 - money drops, he occasionally visited Boston and helped with the

organization's on-the-ground work. For instance, Castillo visited

Boston and helped Castro check for police presence before a money

drop on August 31, 2020. And on December 14, 2020, Castillo again

spent time in Boston -- including at a stash house at 800 Hyde

Park Avenue with Heraux and Castillo -- before flying back to

Mexico.

The drug organization primarily operated out of an

apartment located at 800 Hyde Park Avenue, where Castro and others

stored and prepared drugs. Members of the drug organization moved

drugs and cash around the city using vehicles that were outfitted

with hidden compartments. Castillo had organized the after-market

installation of these compartments. In January 2021, officers

searched one of these vehicles after having observed Heraux use it

to conduct a money drop and found $150,000 in the hidden

compartment. After months of surveillance, on March 23, 2021,

law enforcement searched 800 Hyde Park Avenue (along with other

locations) and seized multiple kilograms of fentanyl and related

paraphernalia. These proceedings ensued.

II. Procedural History

A. Pretrial Proceedings

On April 15, 2021, a federal grand jury sitting in

Massachusetts returned a two-count indictment charging Castillo

and seven co-defendants -- including Castro and Heraux -- with

- 3 - (1) conspiracy to distribute and possess with intent to distribute

400 grams or more of fentanyl and cocaine, in violation of 21

U.S.C. § 846; and (2) money laundering conspiracy, in violation of

18 U.S.C. § 1956(h).1 The district court issued an arrest warrant

for Castillo that day.

In January 2022, Castillo was arrested in the Dominican

Republic and flown to the United States. On April 10, 2023,

Castillo moved to dismiss the indictment on the basis of alleged

outrageous government misconduct. He argued that his arrest in

the Dominican Republic by officers who he believed were U.S.

Marshals violated the due process clause, Department of Justice

policy, and the Mansfield Amendment to the Foreign Assistance Act,

22 U.S.C. § 2291(c).2 The government maintained that Dominican

officers executed the arrest pursuant to a Dominican warrant and

that, even if the arrest had been executed by U.S. agents, it did

not comprise misconduct sufficiently outrageous to merit the

indictment's dismissal.

The district court held a hearing on the motion to

dismiss. After hearing argument, the court found that, even

1By the time of trial, the operative charging document was a superseding indictment dated May 3, 2023, which charged Castillo and Heraux only with the same counts. The charged time period in the superseding indictment spanned March 2020 to March 23, 2021. 2The Mansfield Amendment limits the power of officers of the United States to effect arrests in foreign countries. See 22 U.S.C. § 2291(c)(1)-(2).

- 4 - assuming that the defendant was arrested by U.S. agents abroad,

the arrest would not "rise to that especial-level of outrageous

government conduct that would warrant the dismissal of a

duly-returned indictment." It denied the motion accordingly.

Castillo then filed two motions in limine that are

relevant to this appeal. Castillo moved to exclude testimony that

provided an "overview" of the conspiracy investigation. Castillo

argued that such evidence would not be relevant; would have

probative value that was outweighed by prejudicial effect; and

would violate his Fifth and Sixth Amendment rights. The court

deferred ruling on the motion, which Castillo filed just a few

days before trial, explaining that it would instead "rule as

questions [we]re asked" at trial. Separately, Castillo sought to

exclude evidence about his participation in drug trafficking

activities prior to the charged time period under Federal Rules of

Evidence 403 and 404(b). The court explained that "the fact that

certain events fall outside the particular charged period of the

conspiracy does not trouble me much because it's a course of

conduct and that's admissible," but that it would likewise "take

it question by question."

- 5 - B. Trial

Because Castillo raises so many challenges relating to

the trial proceedings, we describe the trial in some detail.

The joint jury trial of Castillo and Heraux began on May

15, 2023. At the outset, the trial judge informed counsel that

"the objection of one defendant is the objection of both." The

judge also instructed that because he "do[es]n't like speaking

objections," in order to object, counsel should "just say, 'I

object,'" and "that's sufficient for [him]."

The government opened its case-in-chief with the

testimony of Trooper Brian Simpkins, the co-case agent leading the

investigation of Castro, Heraux, and Castillo. Simpkins testified

that, in the course of investigating another individual, he learned

that Castro was selling drugs and opened an investigation. A

wiretap of Castro's communications led Simpkins to begin

investigating Heraux, as well. This led to the discovery of six

vehicles used by the targets that law enforcement would later

discover were outfitted with hidden compartments that were used to

store drugs or money. Two of these vehicles were registered to

Castillo's brother. After another of the vehicles was used to

deliver a sample of fentanyl to an informant, Simpkins opened an

investigation into Castillo.

The investigation led Simpkins to identify various

locations associated with the drug operation, including the stash

- 6 - house at 800 Hyde Park Avenue. It also led the government to tap

a number of phones, including a phone used by Castro which was in

contact with Heraux and Castillo.

Simpkins observed a few salient interactions during the

investigation. On August 26 and 31, 2020, he observed Heraux make

deliveries of cash to an undercover officer and two women,

respectively. On December 14, 2020, while Simpkins was following

one of the vehicles registered to and used by Heraux, he saw

Castillo. Castillo drove to 800 Hyde Park Avenue. Data from

Heraux and Castro's phones indicate that they, too, were at 800

Hyde Park Avenue that day. On January 8, 2021, Simpkins observed

Heraux conduct another money drop. An officer stopped Heraux's

vehicle, which Simpkins then searched. Simpkins found $150,000 in

the vehicle's hidden compartment.

On March 23, 2021, Simpkins and other officers executed

a number of search and arrest warrants. Simpkins arrested Heraux

at his residence, where Simpkins also found keys to 800 Hyde Park

Avenue and a temporary license for Castillo. At 800 Hyde Park

Avenue, agents found ledgers, drug paraphernalia, and multiple

kilograms of fentanyl.

The government then presented testimony from Castro.

Castro had already pled guilty to conspiracy to distribute fentanyl

and conspiracy to commit money laundering. He testified for the

government in hopes of receiving a lighter sentence -- a fact that

- 7 - counsel made clear to the jury. Castillo's defense rested in large

part on challenging Castro's credibility. Castro testified as

follows.

Castro had known Castillo since the pair's teenage

years. In 2004, Castro entered the U.S. illegally and began

selling drugs in Boston before turning to work with Castillo at

Castillo's parents' bodega. However, Castro went back to drug

dealing and was arrested and deported. He returned to the U.S.,

again illegally, and lived for a time with Castillo in Boston. In

2017, Castro began selling fentanyl with Castillo, Heraux, and

others. They stored the drugs at 800 Hyde Park Avenue. During

this time, Castro and Castillo prepared the drugs and picked up

the money from drug sales, but sent Heraux and an associate to

deliver the drugs using the cars with hidden compartments.

Castro testified that from 2019 to 2021 -- which

includes the charged time period -- Castillo primarily lived in

Mexico with his girlfriend, although he traveled back and forth to

Boston. This left Castro "in charge" of the drug operation in

Boston. During this time, Castro would communicate with Castillo

through WhatsApp using different phone numbers in hopes of avoiding

detection by authorities. Castillo would message Castro with a

phone number of an intermediary and Castro would send Heraux or

another associate to pick up fentanyl from that intermediary.

Castillo would provide Castro with the information of customers to

- 8 - deliver fentanyl to, as well as instructions about what to do with

the cash received in exchange. When Castillo visited Boston, he

helped the drug operation by, among other things, preparing drugs

and assisting with money drops. Castro identified a number of

specific times that Castillo helped out in this manner; for

example, Castillo accompanied Castro when he conducted

countersurveillance for the August 31 money drop.

The government also offered testimony from Detective

Lucas Hernandez, who described some of the money laundering that

occurred in the case. Hernandez testified that he worked

undercover during the investigation by posing as a courier who

helped launder money. On April 17, 2020, Hernandez picked up

$130,000 from Heraux and an associate pursuant to a conversation

with Castro. Hernandez put the money in an undercover bank

account, then wired the money to a Colombian money broker in charge

of paying the money out to a Mexican money broker who had arranged

the transaction. The funds were eventually paid out in Mexico.

On August 26, 2020, September 24, 2020, and February 1, 2021,

Hernandez participated in similar transactions involving Castro

and Heraux to help launder another $100,000, $75,000, and $100,000,

respectively. Those funds, too, moved through a Colombian money

broker to be paid out in Mexico.

The government offered the corroborating testimony of

another undercover officer, Alex Hernandez, who assisted Lucas

- 9 - Hernandez with some of the money laundering operations. Alex

Hernandez further testified about a money laundering operation

that he participated in on December 10, 2020. He had arranged the

operation by communicating with a phone number ending in 6450,

which circumstantial evidence suggested was used by Castillo.

The government then offered the testimony of the other

co-case agent on the investigation, Mark Concannon. Concannon

introduced various pen register records -- that is, information

about the phone numbers that a target phone calls and texts -- that

were used in the investigation. Concannon testified that pen

registers were used to identify additional targets and verify that

wiretaps were working properly. He introduced pen register data

indicating that members of the drug organization, including Heraux

and Castro, messaged each other over WhatsApp in December 2020.

Concannon also introduced evidence of a $1,000 money transfer

Castro sent to Sinaloa, Mexico, in November 2019.

Castillo's defense throughout the trial relied primarily

on challenging Castro's credibility and highlighting the indirect

nature of the evidence against Castillo. Nevertheless, on May 23,

the jury found Castillo and Heraux guilty on both counts.

C. Sentencing

In November 2023, the district court sentenced Castillo

to 25 years of imprisonment: 25 years on the drug conspiracy charge

- 10 - and 20 years on the money laundering conspiracy charge, to run

concurrently. Castillo timely appealed.

As relates to this appeal, over six months later in a

different criminal proceeding, the same court sentenced Castro to

a total of 39 months of incarceration for his participation in the

conspiracy.

III. Discussion

Castillo now challenges the district court's refusal to

dismiss the indictment before trial; certain evidentiary rulings;

instructions; and aspects of sentencing. We address each in turn.

A. Motion to Dismiss for Outrageous Government Conduct

We begin with Castillo's challenge to the indictment

before turning to his trial-related arguments. We review the

denial of the motion to dismiss the indictment de novo. United

States v. Anzalone, 923 F.3d 1, 5 (1st Cir. 2019) (citing United

States v. Luisi, 482 F.3d 43, 58 (1st Cir. 2007)).

Castillo asks us to evaluate his position, first raised

in his motion to dismiss below, that the trial court should have

dismissed the indictment for "outrageous government conduct." He

reiterates that his arrest in the Dominican Republic comprised

outrageous government conduct because U.S. Marshals conducted the

arrest in a foreign country, violating his due process rights,

Department of Justice policy, and the Mansfield Amendment, 22

- 11 - U.S.C. § 2291(c). There was some disagreement before the district

court about whether the U.S. Marshals actually effected Castillo's

arrest; the court made no factual findings on the matter, but

rather assumed that the facts set forth by the defendant were true.

We take the same approach. See United States v. Therrien, 847

F.3d 9, 14 (1st Cir. 2017).

The presence of "outrageous government misconduct"

permits a district court to dismiss criminal charges in "very rare

instances when the government's misconduct is so appalling and

egregious as to violate due process by 'shocking . . . the

universal sense of justice.'" Id. (omission in original) (quoting

Luisi, 482 F.3d at 59). For example, a case may constitute

outrageous government misconduct if (i) law enforcement officers

"engineer" or "direct" a crime "from start to finish," id. at 15

(citing United States v. Sneed, 34 F.3d 1570, 1577 (10th Cir.

1994)); (ii) there are "sexual relations between defendants and

government agents," such as where the government "consciously set

out to use sex as a weapon in its investigatory arsenal," id.

(quoting United States v. Cuervelo, 949 F.2d 559, 567 (2d Cir.

1991)); or (iii) "government agents physically or psychologically

abuse[]" a defendant, id. at 16 (citing United States v. Santana,

6 F.3d 1, 4 (1st Cir. 1993)). The shocking nature of these

benchmarks helps explain why, to date, a claim of outrageous

- 12 - government misconduct has "never succeeded in our Circuit."

Anzalone, 923 F.3d at 6.

Nor will this case be the first. The participation of

U.S. law enforcement officers in a foreign arrest does not,

standing alone, comprise outrageous government misconduct meriting

dismissal of underlying criminal charges. Cf. United States v.

Alvarez-Machain, 504 U.S. 655, 657 (1992) (holding that defendant

who was "forcibly kidnaped" from Mexico at the direction of DEA

agents did not "thereby acquire[] a defense to the jurisdiction of

this country's courts"). Castillo has offered no authority in

support of his novel position that violations of the Mansfield

Amendment or Department of Justice policy, on their own, comprise

"outrageous government misconduct." Indeed, these alleged

violations fall far short of types of misconduct that we have

suggested would be "outrageous." See Therrien, 847 F.3d at 15-16

(listing examples). They fall far short of the standard set for

outrageous government misconduct in other circuits, as well. See,

e.g., United States v. Twigg, 588 F.2d 373, 380-81 (3d Cir. 1978)

(outrageous government misconduct where government supplied

defendants with key ingredient and know-how to make drugs,

purchased drug-making supplies, and secured laboratory location,

without which defendants could not have made drugs). The purported

violations here involved only U.S. Marshals arresting Castillo

abroad without "advance approval" from the Department of Justice.

- 13 - This course of action hardly "shock[s] . . . the universal sense

of justice." Therrien, 847 F.3d at 14 (quoting Luisi, 482 F.3d at

59). We accordingly affirm the district court's refusal to dismiss

the indictment.

B. Evidentiary Objections

We turn to Castillo's trial-related claims, beginning

with his evidentiary challenges. Castillo challenges the

admission of certain evidence of his prior drug-dealing activity;

pen register data; evidence of a wire transfer to Sinaloa, Mexico;

and certain "overview" testimony. He also argues that these

alleged errors in the aggregate require reversal of his conviction.

As we will explain below, Castillo preserved some -- but

not all -- of these challenges by raising them to the trial court.

We review preserved evidentiary objections for abuse of

discretion. United States v. Maldonado-Peña, 4 F.4th 1, 29 (1st

Cir. 2021) (quoting United States v. Colón-Díaz, 521 F.3d 29, 33

(1st Cir. 2008)). If a trial court abused its discretion in its

evidentiary ruling, "then we vacate the conviction unless the error

was harmless." United States v. García-Sierra, 994 F.3d 17, 26

(1st Cir. 2021) (citing United States v. Brown, 669 F.3d 10, 24

(1st Cir. 2012), and Fed. R. Crim. P. 52(a)). An error is harmless

when the judgment "was not substantially swayed by the error."

United States v. Villa-Guillen, 102 F.4th 508, 515 (1st. Cir. 2024)

- 14 - (quoting United States v. Burgos-Montes, 786 F.3d 92, 114 (1st

Cir. 2015)).

We review unpreserved challenges, on the other hand, for

only plain error. See United States v. Leoner-Aguirre, 939 F.3d

310, 320 (1st Cir. 2019); Fed. R. Crim. P. 52(b). Plain error

familiarly requires "(1) that an error occurred (2) which was

clear or obvious and which not only (3) affected the defendant's

substantial rights, but also (4) seriously impaired the fairness,

integrity, or public reputation of judicial proceedings." United

States v. Encarnacion, 26 F.4th 490, 504 (1st Cir. 2022) (quoting

United States v. Duarte, 246 F.3d 56, 60 (1st Cir. 2001)). The

plain error standard is demanding in recognition that typically "a

defendant must timely -- and specifically -- raise an evidentiary

objection to preserve his or her appellate rights." United States

v. Pires, 138 F.4th 649, 664 (1st Cir. 2025). It is a backstop to

ensure that the appellate court may "correct 'blockbusters'" but

does not reach "ordinary backfires which may mar a trial record."

United States v. Madsen, 809 F.3d 712, 717 (1st Cir. 2016) (cleaned

up) (quoting United States v. Griffin, 818 F.2d 97, 100 (1st Cir.

1987)).

This case involves one unusual consideration in our

assessment of preservation: the trial judge instructed counsel not

to explain their speaking objections during the trial. Typically,

"[t]o preserve a claim of error for appellate review, an objection

- 15 - must be sufficiently specific to call the district court's

attention to the asserted error." United States v. Perez-Delgado,

99 F.4th 13, 20 (1st Cir. 2024) (quoting United States v.

Soto-Soto, 855 F.3d 445, 448 n.1 (1st Cir. 2017)). At the same

time, we do not require "exquisite precision" and can consider the

overall context of the objection to assess whether it was

preserved. Id. (quoting United States v. Rivera-Berríos, 968 F.3d

130, 134 (1st Cir. 2020)). When determining whether Castillo

preserved his evidentiary claims, then, we consider his objections

in their overall context, including the trial court's response, to

most fairly determine the basis upon which the objection was

lodged. See, e.g., Villa-Guillen, 102 F.4th at 521 n.11 (using

what the "district court understood" as a basis for determining

preservation). In addition, because the trial judge informed the

parties that "the objection of one defendant is the objection of

both," we follow suit and treat any objections lodged by Heraux's

counsel as preserved by Castillo. See United States v. Sepulveda,

15 F.3d 1161, 1180 (1st Cir. 1993) (taking the same approach).

1. Evidence of Prior Drug-Dealing

Castillo first submits that the trial court abused its

discretion in admitting evidence related to certain prior

drug-dealing activity in violation of Federal Rules of Evidence

404(b) and 403. He challenges the admission of testimony from

Trooper Simpkins about a fentanyl sample delivery in January 2019,

- 16 - before the beginning of the charged time period, as well as

Castro's testimony about participating in drug dealing with

Castillo before the charged time period.

Castillo had sought to exclude evidence about his prior

drug-dealing activity in a motion in limine filed days before trial

began. That motion sought to exclude any testimony from Castro

about Castillo's "drug trafficking and money-laundering

activities" prior to the dates of the charged conspiracy, including

an instance in January 2019 in which Castillo delivered a sample

of fentanyl. The court explained orally at the start of trial two

days later that it was not "trouble[d] that 'certain events f[e]ll

outside the charged period of the conspiracy . . . because it's

a course of conduct and that's admissible.'" It noted, however,

that it was "not ruling" on the motion in limine but would instead

"take it question by question."

i. Trooper Simpkins' Testimony About the 2019 Sample Delivery

We first address Castillo's challenge to Trooper

Simpkins' testimony about the 2019 sample delivery. At trial,

Simpkins testified that he saw a certain car3 be used, by

unspecified people, to deliver a sample of fentanyl. Castillo

objected on unspecified grounds, which the court overruled.

3 Simpkins had testified that the car was registered to a courier of Castillo's, but, in response to Castillo's objection, the court struck that testimony.

- 17 - Immediately after asking about the sample delivery, the government

elicited testimony that Simpkins began an investigation into

Castillo after the sample delivery. Castillo did not object when

the government elicited this testimony.

We begin by briefly addressing the latter, unpreserved

point: to the degree that Castillo challenges Simpkins' testimony

that he opened an investigation into Castillo after observing the

fentanyl sample delivery, he has waived the argument. Where a

party neither objects to testimony below nor provides a plain error

analysis in his opening brief, he waives the challenge. See United

States v. Rathbun, 98 F.4th 40, 58 (1st Cir. 2024).

We turn to the only remaining evidence for our review:

Simpkins' testimony that he saw a sample of fentanyl be delivered.

Prior to trial, Castillo argued that any evidence of the January

2019 fentanyl sample delivery should have been excluded. Although

the motion in limine addressed only anticipated testimony from

Castro, when considered in conjunction with Castillo's

contemporaneous objection and the district court's instruction not

to specify objections, we assume that the issue is preserved and

review the court's decision for abuse of discretion. See United

States v. Simon, 12 F.4th 1, 48 (1st Cir. 2021).

Federal Rule of Evidence 404(b)(1) prohibits the

introduction of evidence of a person's prior "crime, wrong, or

act" to show that the person has a propensity to commit such

- 18 - crimes, wrongs, or acts. However, prior-bad-acts evidence may be

admitted to prove a non-propensity purpose such as "motive,

opportunity, intent, preparation, plan, knowledge, identity,

absence of mistake, or lack of accident." Fed. R. Evid. 404(b)(2);

see also United States v. Henry, 848 F.3d 1, 8 (1st Cir. 2017).

If prior-bad-acts evidence is admissible under Rule 404(b)(2), the

court considers whether it should nevertheless exclude it under

Rule 403. The court may exclude evidence under Rule 403 "if its

probative value is substantially outweighed by a danger

of . . . unfair prejudice." Fed. R. Evid. 403. "The standard for

exclusion under Rule 403 is a high one," United States v.

Soler-Montalvo, 44 F.4th 1, 16 (1st Cir. 2022), and it is a "rare

case where we are prepared to second-guess the district court's

Rule 403 analysis," Henry, 848 F.3d at 10.

The trial court did not abuse its discretion in

permitting Simpkins' limited testimony about the sample delivery.

When Castillo's counsel objected to the line of questioning,

Simpkins had testified only that a sample delivery occurred, not

that Castillo had participated in it. At that point, the jury had

heard no testimony from which it could infer that Castillo was

involved in the sample delivery at all. The testimony therefore

did not implicate Rule 404. And the challenge to Simpkins' ensuing

testimony that he then started an investigation of Castillo, as

discussed above, is unpreserved and waived.

- 19 - Even if we assumed without deciding that the trial court

abused its discretion in permitting Simpkins' limited testimony

about the sample delivery, we could not find reversible error in

the instant case. See Lucy v. Gardino, 791 F.2d 980, 986 (1st

Cir. 1986) ("We have previously held that in order to determine

harmless error 'a reviewing court must assess the record as a whole

to determine the impact of the improper evidence upon the jury....

The prejudicial effect of the improper evidence must be weighed

against the weight of the properly admitted evidence.'" (quoting

Morgan v. Hall, 569 F.2d 1161, 1166 (1st Cir. 1978))). Reviewing

the record, it is clear that the government's case as a whole

relied on direct testimony from Castro that Castillo participated

in the drug operation in numerous ways throughout the charged time

period. Castro's testimony was supported by a wide variety of

circumstantial evidence, including recorded phone calls and video

and personal observations by surveilling law enforcement. On those

facts, it is unlikely that an opaque suggestion from Simpkins'

testimony that Castillo may have been involved in a 2019 fentanyl

sample delivery affected the verdict.

ii. Castro's Testimony About Castillo's Prior Drug-Dealing

Castillo next takes aim at Castro's testimony about

dealing drugs with Castillo prior to the charged time period.

Castillo argues that this constituted impermissible propensity

evidence because it encouraged the jury to infer that, because he

- 20 - had dealt drugs from 800 Hyde Park Avenue in the past, he was more

likely part of a later conspiracy dealing drugs from that location.

Castillo preserved this issue: he objected multiple

times to Castro's testimony about pre-2020 drug operations,

including to the "line of questioning regarding the entire

operation that is not part of this charged conspiracy." We

accordingly review for abuse of discretion. Simon, 12 F.4th at

48.

Castillo acknowledges that Rule 404(b)'s permissible

purposes include demonstrating "co-conspirators' relationship of

mutual trust." United States v. Weadick, 15 F.4th 1, 18 (1st Cir.

2021). And although Castillo gestures at arguing that Castro's

testimony nevertheless violated Rule 404(b), he waived the

argument by doing so only in a perfunctory footnote. See Tax-Free

Fixed Income Fund for P.R. Residents, Inc. v. Ocean Cap. LLC, 137

F.4th 6, 24 (1st Cir. 2025) ("We have repeatedly held that

arguments raised only in a footnote or in a perfunctory manner are

waived." (quoting P.R. Tel. Co. v. San Juan Cable LLC, 874 F.3d

767, 770 (1st Cir. 2017))). Instead, Castillo primarily argues

that the admitted evidence violated Rule 403 because it was

unnecessary and minimally probative to demonstrate a relationship

of mutual trust, given the evidence about his decades-long

relationship with Castro, as compared to the prejudicial risk of

an impermissible propensity inference.

- 21 - But even assuming that the district court erred in

admitting Castro's testimony about pre-2020 drug operations, we

find no reversible error. As explained above, the record

illustrates that the government's case relied on Castro's

supported testimony about Castillo's participation in the drug

operation during the charged time period. Thus, it is unlikely

that Castro's testimony about pre-2020 drug operations affected

the verdict.

2. Pen Register Data

Castillo moves on to assert that information collected

by pen registers and compiled by the government was inadmissible

hearsay to which the business records exception, Fed. R. Evid.

803(6), did not apply. In Castillo's telling, certain admitted

exhibits consisted of information provided by phone companies and

then compiled by the Drug Enforcement Administration ("DEA"), but

the government did not offer evidence that the business records

exception applied to the information collected by the phone

companies. It only offered evidence showing that the DEA compiled

the data in the regular course of its practice, which, Castillo

says, is not sufficient to permit the introduction of the

underlying data. The government rejoins that pen register data is

not hearsay at all because it is not an assertion by a person: it

- 22 - is machine-generated data collected in real time pursuant to court

order.

As an initial matter, it is not clear that Castillo

preserved the challenge to the admission of the pen register data.

Heraux's counsel objected to the admission of two exhibits that

contained pen register data, Exhibits 206 and 210, for unspecified

reasons. The trial judge overruled the objections for equally

unspecified reasons. The record does not suggest that either the

objection or the responsive ruling was based on a hearsay

objection. At the same time, it is difficult to fault counsel for

this opacity given that the judge directed the parties not to state

the grounds for speaking objections at the start of trial and later

told counsel that he did not "see the necessity" for a more fulsome

explanation of the objection to Exhibit 206. We assume without

deciding, then, that the issue was preserved because Castillo loses

under both abuse of discretion and plain error review. See United

States v. Soto, 799 F.3d 68, 97 n.17 (1st Cir. 2015) (taking the

same approach).

During the government's case-in-chief, Trooper Simpkins

explained that a pen register collects data about a target phone's

interactions with other phone numbers but that it does not capture

the content of any calls or messages. Simpkins testified that, in

this investigation, pen registers were installed at the same time

as wiretaps to make sure that the wiretaps were working properly.

- 23 - The witness who introduced the pen register exhibits themselves,

Officer Concannon, further explained that "[a] pen register is a

court order for a telephone number that goes to the service

provider, and the service provider then gives [the DEA] the calls

and the text message ingoing and outgoing from the number."

Specifically, "[p]ursuant to the order, the data is collected into

a database that [the DEA] ha[s] that uploads all the information."

The data that the pen registers collected in this case include

subscriber information associated with the target number; the date

and time of incoming or outgoing calls; the phone number contacted;

and location and IP address information. Thus, the information

gathered by pen registers in this case was generated by the

provider mechanically, rather than by a person.

"Hearsay" is a statement made by a "declarant," who is

a "person." See Fed. R. Evid. 801. A machine (at least in 2025)

is not a person. In the ordinary course, then, machine-generated

data is not hearsay. See, e.g., United States v. Miller, 982 F.3d

412, 437 (6th Cir. 2020) ("[Courts] have recognized that

machine-generated information does not qualify as 'hearsay' under

the rules of evidence because the information is not a statement

by a person."); United States v. Channon, 881 F.3d 806, 810–11

(10th Cir. 2018) (machine-generated transaction records in Excel

spreadsheets are not hearsay); United States v. Lizarraga-Tirado,

789 F.3d 1107, 1109-10 (9th Cir. 2015) (location markers generated

- 24 - on image by Google Earth are not hearsay because Google Earth is

not "a person"); United States v. Washington, 498 F.3d 225, 230-31

(4th Cir. 2007) (raw data generated by machines using a "common

scientific and technological process" are not hearsay); United

States v. Lamons, 532 F.3d 1251, 1263-64 (11th Cir. 2008)

("statements of machines" that are not altered by humans are not

hearsay). The premise of Castillo's position, then -- that the

data from the pen register given by the provider to DEA is hearsay

in the first place -- does not bear weight. We conclude that the

district court did not abuse its discretion in admitting the

exhibits.

Contrary to Castillo's assertions, our decisions in

United States v. Benavente Gomez, 921 F.2d 378 (1st Cir. 1990),

and United States v. Moore, 923 F.2d 910 (1st Cir. 1991), do not

require a different result. In Benavente, we addressed a challenge

to the admission of telephone toll records under Federal Rule of

Evidence 803(24), the residual hearsay exception. 921 F.2d at

383-84. In conducting our analysis, we did not consider whether

the data at issue was, in fact, hearsay. Id. We accordingly do

not think that Benavente directs the outcome here. And in Moore,

we agreed that "loan histories" that were created by humans, stored

on a computer, and then printed out from the computer were hearsay

(in fact, no party to that case took the position that they were

not). 923 F.2d at 914. Moore, too, does not bear on the current

- 25 - case. Where the underlying information in a document is made by

a person, the mere involvement of a machine in assembling that

information does not render the underlying assertion non-hearsay.

See id. By contrast, information or data that a machine

automatically collects is not a statement by a person and is

therefore not hearsay.

Finally, Castillo challenges the admission of exhibits

containing a subset of already-admitted pen register data. He

faults inconsistencies between admitted exhibits 206 and 210 and

their sub-exhibits 206.2 and 210.2. The trial court admitted

sub-exhibits 206.2 and 210.2 after Concannon testified that they

contained subsets of the data contained in exhibits 206 and 210

(which had already been admitted). Because Heraux's counsel

objected to the sub-exhibits, we review their admission for abuse

of discretion.

This argument is unavailing because even were it error

to admit the sub-exhibits, that error was harmless. Castillo has

not articulated any manner in which the admission of the

sub-exhibits -- as opposed to the main exhibits -- allegedly

prejudiced him. See United States v. Carbone, 110 F.4th 361,

383-84 (1st Cir. 2024) (no prejudice where defendant fails to

explain theory of how prejudice resulted). Castillo says that the

government's reference to the pen register records in closing

argument caused prejudice, but he does not point to any instance

- 26 - in which the government referenced or relied specifically on the

sub-exhibits. Nor do we see anything else in the record indicating

that the government relied on the sub-exhibits themselves. Even

were there error, then, we have "a fair degree of assurance that

the erroneous ruling did not substantially sway the jury." Id.

(quoting Ruiz-Troche v. Pepsi Cola of P.R. Bottling Co., 161 F.3d

77, 87 (1st Cir. 1998)).

3. Wire Transfer to Sinaloa

Castillo next argues that evidence of a single $1,000

wire transfer to Sinaloa, Mexico, should have been excluded under

Rule 403. Castillo contends that this evidence was not relevant

and that it improperly suggested that Castillo was affiliated with

the Sinaloa cartel, which caused unfair prejudice.

Castillo objected below to the admission of the exhibit

documenting the wire transfer on the grounds of its relevance. He

made no objection on the basis of unfair prejudice. Instead, after

the government explained its theory of the exhibit's relevance,

the court asked if Castillo withdrew his objection. Counsel did

not respond and the exhibit was admitted. The trial court, then,

had no "notice of the error" and no opportunity to conduct the

balancing test set forth in Rule 403. Perez-Delgado, 99 F.4th at

20 (quoting United States v. Colón-Cordero, 91 F.4th 41, 50 (1st

Cir. 2024)). At most, then, our review of this unpreserved

- 27 - challenge is for plain error. United States v. Rivera Calderón,

578 F.3d 78, 95 (1st Cir. 2009).

Castillo hastily mentions a plain error argument in his

brief. But he puts no "flesh on its bones." United States v.

Severino-Pacheco, 911 F.3d 14, 20 (1st Cir. 2018) (quoting United

States v. Zannino, 895 F.2d 1, 17 (1st Cir. 1990)). When an

appellant "fails to even attempt to explain how the plain error

standard has been satisfied," he waives the argument. Id.

Castillo has accordingly waived his claim that admitting the wire

transfer evidence was plain error.

4. "Overview" Testimony

Next up is Castillo's claim that the district court erred

in admitting multiple instances of "overview testimony."

"Typically, '[a]n overview witness is a government agent who

testifies as one of the prosecution's first witnesses

and . . . provides an overview or roadmap of the prosecution's

case to come.'" United States v. Reyes, 24 F.4th 1, 22 (1st Cir.

2022) (omission in original) (quoting United States v. Etienne,

772 F.3d 907, 913 (1st Cir. 2014)). Overview testimony "based on

the results of the agency's overall investigation, rather than on

[the witness's] own personal knowledge or participation," is

disfavored. Id. (quoting Etienne, 772 F.3d at 913-14).

- 28 - We assess each instance of alleged impermissible

overview testimony.4 Castillo first challenges Trooper Simpkins'

testimony during cross-examination by Heraux's counsel that

Simpkins thought that a certain phone was "used by Castillo."5

Heraux's counsel asked Simpkins if certain "paperwork" about the

phone "was targeting Mr. Castro." Simpkins replied, over the

government's objection, that the phone was "used by Mr. Castillo."

Castillo's counsel moved to strike the answer. The court then

questioned Simpkins directly, clarifying that Simpkins had

obtained the information that Castillo used the phone number from

an undercover officer and that Simpkins did not have personal

knowledge that Castillo used the number. The court concluded,

"[w]e'll let that stand for what it's worth," reaffirming that the

witness "personally d[id not] know."

This exchange bears none of the hallmarks of

impermissible overview testimony. Trooper Simpkins provided this

testimony in response to questions posed by Heraux's counsel on

4 Castillo nests some other evidentiary challenges in the "overview testimony" section of his brief. For example, he offers a list of testimony that he says violates the rule against hearsay, the best evidence rule, authentication requirements, and the Due Process Clause. But because Castillo does not explain how the challenged testimony violates the cited rules, he waives these challenges. See United States v. Zannino, 895 F.2d 1, 17 (1st Cir. 1990). 5 Castillo also cites to Trooper Simpkins' separate testimony on direct examination that Castillo used the phone in question; however, the trial court struck that testimony.

- 29 - cross-examination, not in response to questioning by the

government. The testimony did not set forth an overview or roadmap

of the investigation. And it was elicited in the context of

explaining how Simpkins had refreshed his recollection to answer

a different question altogether. We do not discern an abuse of

discretion in permitting this testimony.

Castillo next takes issue with Concannon's

identification of the property management company that managed 800

Hyde Park Avenue. Concannon testified that he had personal

knowledge that a certain company was the property manager for the

building. The testimony was based on his personal knowledge as

co-case agent on the investigation. We do not see how this,

either, would amount to impermissible overview testimony.

We turn to testimony from Trooper Simpkins that the

government elicited after showing Simpkins certain documents to

refresh his recollection. Castillo theorizes that Simpkins had no

personal knowledge from which his recollection could be refreshed.

This theory appears to be completely speculative. Simpkins

testified that the documents jogged his independent memory of the

investigation and that he was not merely "reading the document."

Castillo's speculation to the contrary is not a sufficient reason

for us to doubt that testimony.

Castillo's last effort is that Concannon impermissibly

used the word "we" when explaining his investigation into another

- 30 - member of the drug operation. He cites United States v.

Vázquez-Rivera, which found use of the collective "we" to be

improper in cases where witnesses use it to offer "'lay opinion[s]'

as to a person's culpable role in a charged crime" that are not

based on their personal perceptions. 665 F.3d 351, 358-59 (1st

Cir. 2011) (quoting United States v. García, 413 F.3d 201, 212 (2d

Cir. 2005)). The present case, however, poses no such issue:

Concannon was the co-case agent who personally participated in the

investigation alongside Trooper Simpkins, who had himself

testified at length about the investigation. If anything, the

jury likely assumed that Concannon used the word "we" to refer to

himself along with his co-case agent Simpkins. The use of "we"

was perfectly proper in this context. And Castillo's challenge to

use of the word "we" in undercover agent Lucas Hernandez's

description of the movement of laundered funds fares no better.

Hernandez testified that funds he picked up in his undercover

capacity moved through a Colombian money broker to be paid out in

Mexico. Castillo baselessly speculates that, because Hernandez

testified that "we" wired the funds, Hernandez did not have

personal knowledge of the funds' movements. Castillo offers no

support for this theory, leaving us with no reason to doubt that

Hernandez testified based on his personal knowledge, as he claimed.

We conclude that all of the challenged "overview"

testimony was appropriately admitted.

- 31 - 5. Cumulative Error

Castillo last contends that the foregoing evidentiary

errors, even if insufficient to merit reversal when considered

alone, require reversal in the aggregate. "[I]n assessing the

force of a claim of cumulative error," we weigh factors

"includ[ing] 'the nature and number of the errors committed; their

interrelationship, if any, and combined effect; how the district

court dealt with the errors as they arose . . . ; and the strength

of the government's case.'" United States v. Padilla-Galarza, 990

F.3d 60, 85 (1st Cir. 2021) (quoting Sepulveda, 15 F.3d at 1196

(omission in original)). We acknowledge that "the cumulative

prejudicial effect of independently innocuous trial errors may

warrant a new trial." United States v. García-Sierra, 994 F.3d

17, 36 (1st Cir. 2021) (citing United States v. Peña-Santo, 809

F.3d 686, 702 (1st Cir. 2015)). "But here, for the same reasons

that we find each of the evidentiary errors which we have

identified harmless, we find them collectively so as well." Id.

C. Prosecutorial Misconduct

We turn to Castillo's prosecutorial misconduct argument.

Castillo submits that the government improperly misstated evidence

and appealed to community emotion in its opening and closing

arguments, comprising prosecutorial misconduct. He agrees that,

because he did not raise the issue below, our review is for plain

- 32 - error. See United States v. Vavic, 139 F.4th 1, 21 (1st Cir.

2025).

When assessing such claims of prosecutorial misconduct,

"the plain error standard requires the court first to determine

whether the challenged comment is obviously improper, that is,

whether the first two prongs of the plain error standard have been

satisfied." United States v. Correia, 55 F.4th 12, 48 (1st Cir.

2022) (quoting United States v. Walker-Couvertier, 860 F.3d 1, 10

(1st Cir. 2017)). If so, we consider whether the improper comment

"'so poisoned the well' that the trial's outcome was likely

affected." United States v. Azubike, 504 F.3d 30, 39 (1st Cir.

2007) (quoting United States v. Joyner, 191 F.3d 47, 54 (1st Cir.

1999)). To make this assessment, we consider "(1) the severity of

the prosecutor's misconduct, including whether it was deliberate

or accidental; (2) the context in which the misconduct occurred;

(3) whether the judge gave curative instructions and the likely

effect of such instructions; and (4) the strength of the evidence

against the defendant[]." United States v. Vázquez-Larrauri, 778

F.3d 276, 283 (1st Cir. 2015) (alteration in original) (quoting

United States v. Kasenge, 660 F.3d 537, 542 (1st Cir. 2011)).

1. Opening Statement

Castillo first takes aim at the government's

characterization in its opening statement of the drug operation as

one in which drugs were sent from Mexico to Massachusetts in

- 33 - exchange for money. He says that there was no evidence that the

fentanyl involved in the case was manufactured in Mexico as opposed

to, say, Massachusetts. And he challenges the government's

characterization of his move to Mexico as intended "to secure a

direct connection of fentanyl supply."

In an opening statement, the government is not

summarizing evidence: no evidence has yet been presented. Instead,

it is providing a roadmap of the evidence it expects to present

over the course of the trial. "Many things might happen during

the course of the trial which would prevent the presentation of

all the evidence described in advance." Frazier v. Cupp, 394 U.S.

731, 736 (1969). For this reason, we typically require more than

an incorrect prediction of the evidence to find prosecutorial

misconduct in an opening statement -- we require "particularized

allegations of bad faith on the part of the government." United

States v. Cruz, 156 F.3d 22, 31 (1st Cir. 1998).

Castillo makes no "particularized allegation[] of bad

faith on the part of the government." Id. In fact, the

government's opening -- although it overstated the extent of

evidence about the fentanyl's provenance in Mexico -- did not

otherwise contain incorrect predictions of the evidence to be

presented. The government did ultimately present evidence

suggesting that money from the drug trafficking operation ended up

in Mexico. And Castro testified that he "suppose[d]" that the

- 34 - fentanyl originated in Mexico. Considered in context, then, we

think that "the evidence presented at trial would have corrected

any jury misperception arising from the government's opening

statement." Id. We also recognize that the government may have

intended to introduce additional evidence about "how drug

organizations routinely work" that may have substantiated its

description of the drugs' Mexican origin; however, the court

(appropriately) warned the government to stick to the facts of the

case at hand.

Even more, any inaccurate emphasis on the drugs'

provenance in Mexico in opening did not prejudice the trial's

outcome. The judge twice informed the jury before trial began

that opening statements (and statements by lawyers in general) are

not evidence. And as we have discussed, "the evidence against the

defendant[]" was strong. Vázquez-Larrauri, 778 F.3d at 283

(alteration in original) (quoting Kasenge, 660 F.3d at 542). We

discern no misconduct -- and certainly no prejudicial

misconduct -- in the government's opening descriptions of the

fentanyl's movement.

In a different vein, Castillo says that emphasizing the

drugs' provenance in Mexico and ensuing transport to Massachusetts

improperly appealed to community emotion. Castillo is correct

that "[i]t is improper to appeal to the 'jury's emotions and role

as the conscience of the community.'" United States v. Canty, 37

- 35 - F.4th 775, 787 (1st Cir. 2022) (quoting United States v.

Avilés-Colón, 536 F.3d 1, 4 (1st Cir. 2008)). But he fails to

point to any impermissibly emotional tenor of the prosecution's

argumentation. Describing fentanyl as "strong" and "pure," as the

government did here, is a far cry from the type of emotional appeal

we have found to be impermissible, such as casting defendants as

"greedy outsiders" who "exploit[ed]" the "suffering" and

"vulnerable" addicts in a community. Canty, 37 F.4th at 786-87.

Castillo further disputes the accuracy of two other

statements that the government made in opening: that he and other

co-defendants went to 800 Hyde Park Avenue (the stash house where

fentanyl was ultimately seized) "over and over," and that officers

"observed these defendants moving around, distributing fentanyl,

and laundering money." We agree that these assertions overstate

the evidence that would eventually be presented with respect to

Castillo. The evidence ultimately showed that Castillo

accompanied Castro on an August 31 money drop after which he

returned to 800 Hyde Park Avenue, and that on December 14, 2020,

a car Castillo was seen in drove to that address. But considered

in the context of the judge's multiple limiting instructions and

the preliminary nature of the comments, we do not think that this

exaggeration "'so poisoned the well' that the trial's outcome was

likely affected." Azubike, 504 F.3d at 39 (quoting Joyner, 191

F.3d at 54).

- 36 - 2. Closing Statement

Castillo also challenges a number of statements made in

closing argument. "[A]n incorrect recitation of either the

evidence or the record in a closing argument may constitute

prosecutorial misconduct." Madsen, 809 F.3d at 717.

Castillo posits that reference to "Sinaloa," Mexico, in

describing a wire transfer improperly prejudiced the jury due to

jurors' likely knowledge of Sinaloa as home to the infamous drug

cartel of the same name. But the inclusion of the word "Sinaloa"

was an accurate characterization of properly admitted evidence.

See supra Part III.B.3; United States v. Veloz, 948 F.3d 418, 436

(1st Cir. 2020) (finding that there is "nothing improper in the

prosecutor referring" to statements that "were properly

admitted"). And Castillo provides no support for his theory that

the prosecution used the word "Sinaloa" in order to improperly

invoke supposed juror prejudice.

Castillo next says that the government's statement that

"money was being dropped off so that it could be sent back to

Mexico where Castillo was residing, waiting to send the next

shipment of drugs to the United States," was unsupported by

evidence. To the contrary, undercover officer Alex Hernandez

testified about three money pick-ups that he participated in which

were "paid out" in Mexico. In conjunction with evidence that

Castillo resided in Mexico and organized drug and money deliveries

- 37 - for Castro to complete, this was no "incorrect recitation" of the

evidence. Madsen, 809 F.3d at 717.

Castillo next posits that the government misstated the

evidence when it said that Trooper Simpkins testified that Castillo

used a phone number ending in 8236. The government admits that

this statement was erroneous because the supporting testimony had

been stricken from the record. Nevertheless, the misstatement did

not prejudice Castillo. "Especially under plain error review, we

must assess the prosecutor's statements 'within the context of the

case as a whole.'" Id. (quoting United States v. Pires, 642 F.3d

1, 14 (1st Cir. 2011)). Independent evidence that was properly

admitted connected Castillo to that phone number. The government's

overall point, then -- that Castillo was connected to the phone

number -- was no misstatement. And again, the court had instructed

the jury that the statements proffered by lawyers in closing

arguments were not evidence. We therefore do not think it "likely

that the misconduct affected the trial's outcome." Canty, 37 F.4th

at 791.

Castillo next says the government misstated evidence

when it told the jury that Castro had testified that he was present

while Castillo was talking to a person in New York who arranged

the August 31 money drop. Castro had in fact testified that he

did not "exactly" remember whether he was there. But the probative

part of Castro's testimony was not that Castro had been physically

- 38 - present to listen to the conversation, but that upon hearing the

recording on the stand, he identified the speaker as Castillo.

The government's misstatement regarding Castro's proximity to

Castillo at the time of the call, then, did not misstate Castro's

testimony in a way that implicates the jury's verdict.

Finally, Castillo challenges the government's

misstatement of the last date on which he communicated with Heraux:

the prosecutor said February 27, rather than February 22. And he

faults the government's misstatement of Hernandez's testimony

recounting asking Castro for drugs: the prosecutor said Castro

said he had to check with "the boss," when Castro actually said

that he had to check with "the woman." Castillo fails to explain

why either misstatement would necessitate a new trial. As the

government points out, it corrected the misstated date in rebuttal.

Again, the judge had just reminded the jury that it was the jurors'

memory of the evidence -- not the lawyers' summary -- that

governs. We determine that neither misstatement prejudiced the

jury's verdict. In sum, no prosecutorial misconduct requiring a

new trial occurred in this case.

D. Jury Instruction on Interstate Commerce

Moving on, we evaluate whether the district court's

failure to instruct the jury on an element of the money laundering

statute amounted to plain error. The parties agree that Castillo

- 39 - did not preserve the issue. We determine that Castillo waived the

plain error argument.

The federal money laundering statute requires that the

illicit financial transaction at issue affect interstate or

foreign commerce. See 18 U.S.C. § 1956(c)(4). The parties agree

that the jury instructions did not describe the interstate or

foreign commerce requirement and that this omission amounted to a

"clear or obvious error." For an error to be plain, though, the

error must also affect a defendant's " substantial rights -- but

even then we can still affirm if [he] does not show as well that

the error seriously harmed the fairness, integrity, or public

perception of [his] trial." United States v. Andino-Rodríguez, 79

F.4th 7, 28 (1st Cir. 2023) (quoting United States v. Cruz-Ramos,

987 F.3d 27, 39 (1st Cir. 2021)).

Castillo does not explain how the incomplete instruction

affected his substantial rights or seriously harmed the fairness,

integrity, or public perception of his trial. He has accordingly

waived the argument that the error here was plain. See United

States v. Velázquez-Aponte, 940 F.3d 785, 800 (1st Cir. 2019)

(defendant "waived his claim of error by failing to address the

fourth prong of plain error review -- that the alleged error

seriously impaired the fairness of the judicial proceedings").

- 40 - E. Sentencing Challenges

Having affirmed Castillo's conviction, we turn to his

claims of sentencing error.

1. Apprendi and Alleyne Error

Castillo asserts that his sentence violated the

principles set forth in Apprendi v. New Jersey, 530 U.S. 466

(2000), and Alleyne v. United States, 570 U.S. 99 (2013). We

review a preserved Apprendi or Alleyne issue de novo. United

States v. Trahan, 111 F.4th 185, 197 (1st Cir. 2024).

Apprendi instructs that "any fact that increases the

penalty for a crime beyond the prescribed statutory maximum must

be submitted to a jury[] and proved beyond a reasonable doubt."

United States v. Pizarro, 772 F.3d 284, 288 (1st Cir. 2014)

(quoting Apprendi, 530 U.S. at 490). Alleyne clarified that

Apprendi applies to any fact that increases the mandatory minimum

penalty for a crime. Alleyne, 570 U.S. at 103. In Castillo's

case, the trial court determined that the drug conspiracy charge

(Count 1) carried an increased mandatory minimum penalty of 15

years' imprisonment pursuant to 21 U.S.C. § 841(b)(1)(A). That

statute prescribes a 15-year mandatory minimum when: (1) the

offense involving "400 grams or more of a mixture or substance

containing a detectable amount of

N-phenyl-N-[1-(2-phenylethyl)-4-piperidinyl] propanamide," 21

U.S.C. § 841(b)(1)(A)(vi), and (2) the defendant had been

- 41 - convicted of a prior serious drug felony in the past, id.

§ 841(b)(1)(A).

Castillo's challenge is premised on a discrepancy

between the language of Section 841(b)(1)(A)(vi) and the jury's

verdict. The jury found that the offense involved 400 grams or

more of "fentanyl" rather than

"N-phenyl-N-[1-(2-phenylethyl)-4-piperidinyl] propanamide," which

is fentanyl's chemical name. Castillo contends that this

discrepancy means that the calculated sentencing range

impermissibly rested on "extra-record speculation" that "fentanyl"

is the same thing as "N-phenyl-N-[1-(2-phenylethyl)-4-piperidinyl]

propanamide."

However, while Castillo objected to the use of the word

"fentanyl" at sentencing, he did not object to the verdict form

itself based on the use of that word nor did he level objections

to the use of that word throughout the trial. Specifically, when

discussing the verdict form, the district court read on the record

that he intended to charge count one as "conspiracy to distribute

and to possess with intent to distribute 400 grams or more of

fentanyl." The objection from Castillo that ensued focused, not

on the word "fentanyl," but on how -- if Castillo is found guilty

of conspiracy to possess and distribute over 400 grams of

fentanyl -- the district court would be able to determine the

specific drug quantity for sentencing purposes.

- 42 - It is true that the record does not contain references

to fentanyl's chemical name. But it is also true that the record

is replete with references to fentanyl, yet devoid of objections

to that term such that it is unconvincing to claim extra-record

knowledge is needed to establish that

N-phenyl-N-[1-(2-phenylethyl)-4-piperidinyl] propanamide is

fentanyl. For example, the jury immediately heard during the

government's opening statement that "[t]his case is about

kilograms and kilograms of fentanyl." There is no indication that

Castillo's counsel objected to the word choice. For these reasons,

Castillo's argument is waived.

2. Procedural and Substantive Reasonableness

Castillo last lodges three complaints about the

reasonableness of his sentence. He seeks review of the sentencing

court's application of the two-level "stash house" enhancement

under the United States Sentencing Guidelines ("guidelines"),

U.S.S.G. § 2D1.1(b)(12); the propriety of the government's

purported reference to a Sinaloa-based cartel during sentencing;

and the 261-month sentencing disparity between himself and Castro.

We review a preserved challenge to the procedural or

substantive reasonableness of a sentence under "a multifaceted

abuse-of-discretion standard," reviewing "the sentencing court's

findings of fact for clear error and questions of law (including

the court's interpretation and application of the sentencing

- 43 - guidelines) de novo." United States v. Aponte-Colon, 104 F.4th

402, 414-15 (1st Cir. 2024) (first quoting United States v.

Sierra-Jiménez, 93 F.4th 565, 569 (1st Cir. 2024), and then quoting

United States v. Carrasquillo-Vilches, 33 F.4th 36, 41 (1st Cir.

2022)); see also United States v. Polaco-Hance, 103 F.4th 95, 100

(1st Cir. 2024).

i. "Stash House" Enhancement

The federal sentencing guidelines provide a two-level

enhancement to a base offense level "[i]f the defendant maintained

a premises for the purpose of manufacturing or distributing a

controlled substance." U.S.S.G. § 2D1.1(b)(12). Castillo

objected to the application of this enhancement because, in his

view, there was insufficient evidence to prove that he "maintained"

the premises. He says that the "only trial evidence" relevant to

the enhancement was that a phone he purportedly used had contacted

the property's management company. Castillo contends that there

was some factual error and that the property management company

did not actually manage the property during the relevant time.

Therefore, according to Castillo, the court committed procedural

error by improperly calculating the guidelines range. See Gall v.

United States, 552 U.S. 38, 51 (2007).

The government must prove that a sentencing enhancement

applies by a preponderance of the evidence. United States v.

González-Santillan, 107 F.4th 12, 18 (1st Cir. 2024). At

- 44 - sentencing, the government summarized other evidence presented at

trial -- besides Castillo's alleged contact with the property

management company -- to show that Castillo "maintained" the

premises at 800 Hyde Park Avenue. This included evidence that

Castillo leased and had keys to the apartment and used the

apartment to conduct drug dealing activity when he was in Boston.

This evidence was sufficient for the sentencing court to find that

Castillo maintained the premises. In addition, the jury found

that "the government proved beyond a reasonable doubt that Fermin

Castillo maintained a premises for the purposes of manufacturing

or distributing a controlled substance." The jury's finding

undergirds our confidence that the sentencing court did not abuse

its discretion by finding, by a preponderance of the evidence,

that the enhancement applied.

ii. Connection to Sinaloa Cartel

We turn to Castillo's argument that the government

inaccurately said that he acted on behalf of "a Sinaloa, Mexico

based [drug trafficking organization]" at sentencing. Castillo

says that the reference may have affected the sentence because

"the government argued it in advocating for the exact 300-month

sentence that the court subsequently imposed." Contrary to

Castillo's representation, the government never mentioned Sinaloa

in either its sentencing memorandum or at sentencing. The

government did argue that Castillo acted on behalf of a Mexico-

- 45 - based drug trafficking organization; however, Castillo does not

describe how the mention of Mexico specifically was procedurally

or substantively unreasonable. The argument accordingly fails.

iii. Sentencing Disparity

Castillo last argues that his sentence is unreasonable

because it is over 20 years longer than Castro's, even though they

were similarly culpable participants in the same conspiracies.

This discrepancy is troubling on its face. We determine, however,

that the sentence was not unreasonable because Castro and Castillo

are not similarly situated co-conspirators, and Castillo has not

shown that his downwardly variant sentence is unreasonable.

Castillo was sentenced to 300 months of incarceration on

November 28, 2023. The sentencing court calculated Castillo's

total offense level as 40 which, in conjunction with his criminal

history category of III, correlated to a guidelines sentencing

range of 360 months to life. Castillo had advocated for a ten-year

sentence, reasoning in part that a ten-year period would minimize

disparities with three other members of the drug organization who

had already been sentenced. For example, one of the organization's

primary drug couriers received a 60-month sentence, and another

lower-level participant received one day time served. At the time,

Castro had not been sentenced. Castillo's counsel noted in his

sentencing memorandum that Castro had "testified to being a

relatively equal participant with Mr. Castillo" and that Castro

- 46 - would "predictably benefit from a government motion to avoid the

applicable statutory minimum." At sentencing, counsel reiterated

his prediction that Castro "is very likely to get a sentence below

the otherwise applicable [guidelines sentencing range] or

mandatory minimum sentence."

Six months later, on June 6, 2024, the same court

sentenced Castro to time served plus four days, amounting to 39

total months of incarceration. This was the sentence that both

the government and Castro's counsel recommended. The district

court calculated Castro's total offense level to be nearly as high

as Castillo's6 and calculated Castro's criminal history category

as II (Castillo's criminal history category was III). Of course,

Castro and Castillo differed in another key respect, too: Castro

had pled guilty and testified for the government at Castillo's

trial.

Castillo now raises both procedural and substantive

reasonableness challenges based on the 261-month discrepancy

between the co-conspirators' sentences. "Where both types of

objections are made, we ordinarily will consider first 'whether

the district court committed any procedural missteps and, if the

sentence is procedurally sound, we then ask whether the sentence

6The sentencing court did not clearly state the exact total offense level; it appears that it was either 37 or close thereto.

- 47 - is substantively reasonable.'" United States v. Reyes-Santiago,

804 F.3d 453, 467-68 (1st Cir. 2015) (quoting United States v.

Rossignol, 780 F.3d 475, 477 (1st Cir. 2015)). "In both contexts,

we review the district court's discretionary judgments for abuse

of discretion, its findings of fact for clear error, and its

conclusions of law de novo." Id. at 468 (quoting United States v.

Reverol-Rivera, 778 F.3d 363, 366 (1st Cir. 2015)).

Castillo asserts that the sentencing court committed

procedural error by failing to acknowledge his predicted disparity

argument that Castro would, in the future, "likely . . . get a

sentence below the otherwise applicable [guidelines sentencing

range] or mandatory minimum sentence." Indeed, sentencing courts

must consider "the need to avoid unwarranted sentence disparities

among defendants with similar records who have been found guilty

of similar conduct." 18 U.S.C. § 3553(a)(6). And although this

focus "is primarily aimed at national disparities, rather than

those between codefendants," we also have "legitimate

concerns . . . if a judge sentences similarly situated

coconspirators or codefendants to inexplicably disparate terms."

United States v. Bishoff, 58 F.4th 18, 25-26 (1st Cir. 2023)

(internal quotation marks omitted) (quoting United States v.

Candelario-Ramos, 45 F.4th 521, 526 (1st Cir. 2022)).

In this case, however, Castro and Castillo are not

similarly situated but are in materially different positions.

- 48 - Castro pled guilty while Castillo did not. We have previously

noted that when one defendant pleads guilty and another does not,

that constitutes a material difference of the kind that would

preclude a disparity claim. See United States v. Rodriguez-Lozada,

558 F.3d 29, 45 (1st Cir. 2009) ("Given the material difference

between the defendants who pled guilty pursuant to plea agreements

and [the defendant] who did not, no disparity in sentencing

occurred in this case that would amount to an abuse of

discretion."). Thus, considering Castro and Castillo's materially

different positions, the sentence disparities between the two does

not amount to a procedural error.

Castillo's substantive unreasonableness argument fares

no better. He says that "[t]here is no reasonable view of the

evidence justifying such a stark divergence based on Castillo and

Castro's relative culpability" even considering Castro's

assistance to the government.

To determine whether a sentence is substantively

reasonable, "we ask 'whether the sentence falls within [the] broad

universe'" of available reasonable sentencing outcomes. United

States v. Concepcion-Guliam, 62 F.4th 26, 36 (1st Cir. 2023)

(quoting United States v. Rivera-Morales, 961 F.3d 1, 21 (1st Cir.

2020)). "A sentence will find a home within this broad universe

if it rests on 'a plausible rationale and . . . represents a

defensible result.'" Id. (omission in original) (quoting Rivera-

- 49 - Morales, 961 F.3d at 21). "And when -- as in this case -- a

defendant challenges a downwardly variant sentence, he must carry

a particularly heavy burden to show that the length of the sentence

imposed is unreasonable." Id. "We rarely find a below-guidelines

sentence to be substantively unreasonable." United States v.

Millán-Machuca, 991 F.3d 7, 32 (1st Cir. 2021); see also United

States v. Floyd, 740 F.3d 22, 39-40 (1st Cir. 2014) ("When, as in

this case, a district court essays a substantial downward variance

from a properly calculated guideline sentencing range, a

defendant's claim of substantive unreasonableness will generally

fail.").

Castillo does not demonstrate that his sentence was

unreasonable. His sentence was a 5-year downward departure from

the guidelines sentencing range of 360 months to life. And our

concern about the stark difference between the length of his

sentence and the length of Castro's is obviated by the fact that

Castro pled guilty, as discussed above. We find that the sentence

is substantively reasonable.

IV. Conclusion

For the foregoing reasons, we affirm Castillo's

conviction and sentence.

- 50 -