United States v. Adamu

• Court: Court of Appeals for the Second Circuit
• Decided: July 21, 2025
• Docket: 23-6561
• Status: Published

Opinion

23-6561(L) United States v. Adamu

United States Court of Appeals for the Second Circuit _____________________________________

August Term 2024 Argued: February 6, 2025 Decided: July 21, 2025

Nos. 23-6561 (Lead), 23-6696 (Con) _____________________________________

UNITED STATES OF AMERICA,

Appellee,

v.

GODOFREDO LEANDRO GONZALEZ, LUIS RAFAEL FEBRES MONASTERIO, MURVIN REIGOUD MAIKEL, OMAR TORRES, MOSES ROOPWAH, NEREDIO-JULIAN SUCRE, DAVID CARDONA-CARDONA, ARGEMIRO ZAPATA-CASTRO, SHERVINGTON LOVELL, STEVEN ANTONIUS, YOUSSOUF FOFANA

Defendants,

JIBRIL ADAMU, JEAN-CLAUDE OKONGO LANDJI,

Defendants - Appellants. _____________________________________

Appeal from the United States District Court for the Southern District of New York No. 1:18-cr-601-9, Paul G. Gardephe, Judge _____________________________________ Before: PARKER, BIANCO, and NARDINI, Circuit Judges.

Defendants-Appellants Jibril Adamu and Jean-Claude Okongo Landji appeal from a judgment of the United States District Court for the Southern District of New York (Gardephe, J.). They were convicted following a jury trial of conspiracy to distribute and to possess with the intent to distribute five kilograms or more of cocaine in violation of Title 21, U.S. Code, Sections 959(c), 959(d), and 963. On appeal, the Defendants contend that (1) the government lacked jurisdiction to prosecute under 21 U.S.C. § 959, (2) the government violated their Sixth Amendment right to counsel by improperly using privileged information at trial, and (3) the district court erred in permitting the government to introduce data extractions from their cell phones. For the reasons set forth, we AFFIRM the judgment of the district court.

FOR APPELLEE: ELINOR L. TARLOW, Assistant United States Attorney (Matthew J.C. Hellman, Nathan Rehn, Assistant United States Attorneys, on the brief), for Damian Williams, United States Attorney for the Southern District of New York, New York, NY.

FOR DEFENDANT-APPELLANT JIBRIL ADAMU: MICHAEL P. ROBOTTI, Ballard Spahr LLP, New York, NY (Kelly Lin, Kathryn, J. Boyle, Ballard Spahr LLP, New York, NY, on the brief).

FOR DEFENDANT-APPELLANT JEAN-CLAUDE OKONGO LANDJI: JONATHAN I. EDELSTEIN, Edelstein & Grossman, New York, NY.

2 BARRINGTON D. PARKER, Circuit Judge:

Defendants-Appellants Jibril Adamu and Jean-Claude Okongo Landji

appeal from a judgement of the United States District Court for the Southern

District of New York (Gardephe, J.). Following a jury trial, they were convicted

on one count of conspiracy to distribute and to possess with the intent to distribute

five or more kilograms of cocaine. See 21 U.S.C. §§ 959(c), 959(d), 963. They were

each sentenced to 120 months’ imprisonment and five years’ supervised release.

On appeal, the Appellants contend that (1) the government lacked

jurisdiction to prosecute under 21 U.S.C. § 959, (2) the government violated the

Sixth Amendment by improperly using information protected by the

attorney-client privilege and (3) the district court erred in permitting the

government to introduce data extracted from their cell phones. For the reasons set

forth below, we AFFIRM the judgment of the district court.

BACKGROUND

This case arises from a multi-year international narcotics trafficking

conspiracy in which Landji and Adamu used a private aircraft to transport multi-

ton shipments of cocaine from South America to Africa and Europe. Landji is a

United States citizen who owned and operated an aviation charter business using a Gulfstream G2 jet, and Adamu was Landji’s co-pilot in the operation that led to

their ultimate arrest.

In 2016, Landji began planning a large-scale drug trafficking operation with

his co-conspirator, David Cardona-Cardona (“Cardona”), a known cocaine

trafficker. Cardona, who testified at trial pursuant to a cooperation agreement,

introduced Landji to Adamu. Landji and Adamu undertook extensive

preparations to conceal and facilitate their operation, which included retrofitting

the G2, conducting test flights, scouting remote landing strips in Western Sahara,

and communicating over secure messaging platforms.

In May 2018, Landji met with three individuals: Cardona, Youssouf Fofana,

one of Cardona’s drug customers, and a confidential DEA informant known as

“Rambo” who posed as a large-scale trafficker. During a series of meetings in

Lomé, Togo, which were covertly recorded and admitted at trial, the conspirators

discussed the logistics of the trafficking plans. The defendants planned to use the

G2 to make “black flights” (i.e., flights with disabled transponders) to transport

multi-ton cocaine shipments by co-mingling narcotics with legitimate cargo.

Landji agreed to a one-kilogram test run to demonstrate the conspirators’ capacity

to move larger quantities of drugs.

4 In October 2018, the defendants finalized their plans for the test flight. They

loaded the G2 with a kilogram of cocaine in Mali and flew it to Zagreb, Croatia.

When they arrived, Croatian authorities arrested both defendants. Along with the

cocaine, the agents seized the defendants’ mobile phones, which contained

messages, videos, and contacts relating to their involvement in the drug

conspiracy. Following the arrests, Adamu made admissions to DEA agents in

which he acknowledged, among other things, his relationship with Cardona and

his awareness that Cardona had previously used aircraft for drug smuggling.

Both defendants were extradited to the United States in October 2019.

During the extradition process, DEA agents accompanying the defendants took

custody of two categories of materials: documents collected by Croatian police (the

“Croatian Law Enforcement Materials”) and a separate set of personal papers

found in the defendants’ luggage (the “Extradition Documents”). The Croatian

Law Enforcement Materials were produced to defense counsel in December 2019.

However, the Extradition Documents were not produced at that time because of

what government agents described as an internal misunderstanding. See United

States v. Landji, No. (S1) 18-CR-601 (PGG), 2021 WL 5402288, at *18 (S.D.N.Y. Nov.

18, 2021). According to the lead prosecutor, the government “mistakenly

5 believed” that the Extradition Documents were duplicative scans of documents

contained within the Croatian Law Enforcement Materials, and, for this reason,

did not review or turn them over with their initial production. Id. However, after

Adamu’s counsel inquired in January 2020 about additional materials seized in

Croatia, the government discovered the oversight. At that point, realizing that the

Extradition Documents might contain potentially privileged information, the lead

prosecutor in charge instructed the investigative team not to review them and

directed a paralegal outside the team to produce them to defense counsel, which

occurred in January 2020.

In October 2020, both defendants moved for the return of the Extradition

Documents contending that they contained privileged attorney-client

communications such as handwritten notes and legal memoranda. Defendants

did not submit sworn declarations in support of their motions. The government

opposed the motions and submitted sworn statements from DEA agents and

prosecutors affirming that none of the materials had been read, apart from

incidental exposure during their seizure and scanning. The district court, finding

the defendants had not demonstrated the documents were privileged, denied the

motion.

6 The issue resurfaced in July 2021 when Landji’s counsel requested to inspect

the original physical documents and discovered that some had not been included

in the earlier production. One such document was a one-page memorandum from

Landji’s Croatian attorney (“the Šušnjar Memorandum”), which defense counsel

argued contained privileged information including an outline of the defendants’

legal strategy. At that point, both defendants renewed their motions for the return

of the documents and sought a hearing pursuant to Kastigar v. United States, 406

U.S. 441 (1972), on the grounds that the government had seen and used privileged

information. In support of the renewed motion, Landji submitted a declaration

stating he had made handwritten notes on certain documents in preparation for

discussions with his attorney. Adamu’s motion referred to a notebook containing

some 100 pages of notes that allegedly were made in anticipation of meetings with

counsel.

The district court held a Kastigar hearing in September and October 2021 and

ultimately denied the motion. The government presented six witnesses—four

DEA agents, a DEA analyst, and the lead prosecutor. The district court found that

they each had credibly testified that they had neither read nor relied upon the

Extradition Documents at any stage of the investigation or prosecution, and that

7 none of the government’s investigatory steps or legal strategies were based on

those Documents. The district court also determined that the only privileged

document was the Šušnjar Memorandum, but that it had never been reviewed by

the government. The district court further concluded that, even assuming some

inadvertent exposure had occurred, it did not taint the government’s case because

it had been developed through independent sources such as proffers from a

cooperating witness and third-party interviews. The district court also ruled, in

the alternative, that any indirect or tangential awareness of privileged material

would not rise to the level of a Kastigar violation.

At trial, the government introduced extensive evidence, including

testimony from Croatian law enforcement, Cardona’s testimony as a cooperating

witness, covert recordings of the May 2018 meetings, electronic communications

between the defendants and their co-conspirators, as well as photographs of the

seized drugs. The jury convicted both defendants. This appeal followed.

On appeal, Defendants argue that (1) the government lacked jurisdiction to

prosecute their offenses under 21 U.S.C. § 959, (2) the government violated their

right to counsel by improperly using privileged information in its prosecution, and

(3) the district court erred in permitting the government to introduce data

8 extractions from the defendants’ cell phones. For the reasons set forth below, we

affirm the judgment of the district court.

DISCUSSION

I. Jurisdiction

Defendants first argue that the United States lacks jurisdiction because 21

U.S.C. § 959 does not criminalize extraterritorial acts of possession with intent to

distribute—the offense for which defendants were convicted. See 21 U.S.C.

§ 959(c). But, as the district court correctly concluded, we have already held that

21 U.S.C. § 959 “appl[ies] extraterritorially in its entirety,” including to “acts of

possession with intent to distribute.” United States v. Epskamp, 832 F.3d 154, 162–

66 (2d Cir. 2016).

Defendants nevertheless contend that Epskamp was wrongly decided and

ask that we revisit that decision. Relying on the D.C. Circuit’s decision in United

States v. Oral George Thompson, they argue that because 21 U.S.C. § 959 gives no

“clear indication” of an extraterritorial application for possession with intent to

distribute, we must conclude that it has none. 921 F.3d 263, 268 (D.C. Cir. 2019).

But Epskamp controls and we see no reason to disregard it for out-of-Circuit

precedent. In any event, it is well settled that one panel of this Court cannot

9 overrule a prior decision of another panel. See, e.g., United States v. Peguero, 34

F.4th 143, 158 (2d Cir. 2022). Accordingly, we conclude that the government had

jurisdiction under § 959.

II. Right to Assistance of Counsel

Next, defendants contend that the prosecution violated the Sixth

Amendment by improperly using privileged documents, and that the district

court thus erred in denying their Kastigar motion. First, defendants argue that the

district court erred in concluding that none of the Croation Law Enforcement

Documents were privileged and that only one of the Extradition Documents—the

Šušnjar Memorandum—fell within the privilege. Second, defendants contest the

district court’s factual determination that the government did not use the

Memorandum in its prosecution. We reject both contentions and conclude that

the district properly denied the Kastigar motions.

To establish a Sixth Amendment violation arising from an invasion of the

attorney-client privilege, a defendant must prove (1) that privileged information

was passed to the government or that the government intentionally invaded the

attorney-client relationship, and (2) that he was prejudiced as a result. United

States v. Ginsberg, 758 F.2d 823, 833 (2d Cir. 1985). To satisfy this test, a defendant

10 must first make a threshold showing that the information is privileged and that

the government actually reviewed it. United States v. Schwimmer, 924 F.2d 443, 445

(2d Cir. 1991). If the defendant establishes that the government reviewed

privileged information, it is not in all instances barred from using the information.

However, the government must prove that the evidence it proposes to use is

derived from a legitimate source “wholly independent” of the privileged

information. See Kastigar, 406 U.S. at 460; see also United States v. Nanni, 59 F.3d

1425, 1432 (2d Cir. 1995). But even if the government used privileged information,

a defendant is still required to show that the government’s conduct was

“manifestly and avowedly corrupt” or that there was “prejudice to [the

defendant’s] case resulting from the intentional invasion of the attorney-client

privilege.” Schwimmer, 924 F.2d at 447.

A. Privileged Material

The District Court correctly concluded that none of the Extradition

Documents except the Šušnjar Memorandum contained privileged information.

These non-privileged documents are a combination of (1) court documents,

highlighted, underlined, or otherwise marked by the defendants, (2) handwritten

notes by defendants, and (3) emails. The district court determined that neither the

11 court documents nor the notes were privileged because there was no “proof that

[their contents] were discussed with a lawyer or intended to serve as an outline of

what would be discussed with a lawyer.” See Landji, 2021 WL 5402288, at *17.

We agree. The Supreme Court has explained that because the privilege has

the effect of withholding relevant information from the factfinder, “it applies only

where necessary to achieve its purpose.” Fisher v. United States, 425 U.S. 391, 403

(1976). Accordingly, in United States v. DeFonte, we reasoned that “[a] rule that

recognizes a privilege for any writing made with an eye toward legal

representation would be too broad.” 441 F.3d 92, 96 (2d Cir. 2006) (emphasis

added). Instead, we look to whether the allegedly privileged information has

actually been communicated to counsel. Id. at 95. This is because “there can be no

violation of the [S]ixth [A]mendment without some communication of valuable

information.” Ginsberg, 758 F.2d at 833. So, while “delivery of the [notes to one’s

attorney] is not necessary” for the privilege to attach, defendants had to

demonstrate that the content of the notes was communicated by the client to the

attorney. DeFonte, 441 F.3d at 96. The district court found that the defendants

failed to make this showing. See Landji, 2021 WL 5402288, at *17.

12 On appeal, the defendants challenge this finding and assert that they did in

fact share the content of the Extradition Documents with their attorneys. But this

determination is a factual one “that will not be reversed unless the district court's

finding is clearly erroneous.” Schwimmer, 924 F.2d at 446. Here, defendants point

to no testimony or anything else in the record to support this argument. While the

defendants claim that they notified their counsel of the seizure of the Extradition

Documents, tellingly, they do not claim that they ever discussed the content of the

documents with their attorneys. Thus, the district court correctly concluded that

the notes did not fall within the attorney-client privilege.

B. Government Review of Documents

The parties concede that one document—the Šušnjar Memorandum—was

privileged. The district court concluded that the government did not review the

document. See Landji, 2021 WL 5402288, at *23–25. The defendants challenge this

factual determination, contending that because there were times that the

prosecution team had access to the Extradition Documents, the government must

have reviewed the Šušnjar Memorandum. This factual conclusion “will not be

reversed unless [it] is clearly erroneous.” Schwimmer, 924 F.2d at 446.

13 We discern no error, clear or otherwise. The evidence presented during

the Kastigar hearings included the testimony of six government witnesses, each of

whom testified that they did not read the substance of the Extradition Documents.

Further, the lead prosecutor testified that he warned a member of the investigative

team not to review the Extradition Documents because they might contain

privileged documents. See Landji, 2021 WL 5402288, at *25. Based on this record,

the district court concluded that the government did not invade the privilege. On

appeal, the defendants offer no non-speculative reasons to disturb those findings

and, consequently, we conclude that the district court committed no error.

C. Wholly Independent Sources

Even assuming arguendo that the government reviewed the Šušnjar

Memorandum, we discern no error, clear or otherwise, in the district court’s

determination that the government derived its evidence from independent

sources. Where the government reviews privileged documents, “[t]he

government must demonstrate that the evidence it uses to prosecute an individual

was derived from legitimate, independent sources.” Schwimmer, 924 F.2d at 446

(citing Kastigar, 406 U.S. at 461–62).

14 The government initially claimed, based on information from Croatian law

enforcement that the G2’s transponders had been turned off for at least part of the

flight, that the test shipment was a “black flight.” Landji, 2021 WL 5402288, at *22.

Prior to trial, however, the government dropped its black-flight theory. The

government asserts that this change was solely based on information provided by

Cardona, the government’s cooperating witness, and Curtis Seal, the third

occupant of the airplane. Defendants, on the other hand, assert that the change

was based on information the government learned through its review of the

Extradition Documents. Defendants contend that “the government articulated no

independent justification for its decision to question witnesses about the black-

flight theory.” Adamu’s Opening Br. at 47. In other words, defendants contend

that even if the government dropped the black-flight theory because of

information it learned from Cardona and Seal, the decision to question them on

the theory was a result of the government’s review of the Šušnjar Memorandum.

The record does not support this contention. It shows that Cardona was

involved in coordinating the logistics of the G2 test shipment, that he had

attempted black-flight drug shipments on prior occasions, and that he had

discussed black flight shipments with the defendants. The record is also clear that

15 “Curtis Seal was [] on the plane” when the arrests occurred. Landji, 2021 WL

5402288, at *25. It was therefore obvious that the government would question

these witnesses on its black-flight theory, irrespective of the contents of the

Extradition Documents and the Šušnjar Memorandum. Accordingly, the district

court did not err, let alone commit clear error.

D. Prejudice

Finally, we agree with the government that any potential error stemming

from the district court’s finding of no invasion, intentional or otherwise, of the

attorney-client privilege in this case was harmless. To find an error harmless, “we

must be able to conclude that the evidence would have been unimportant in

relation to everything else the jury considered on the issue in question, as revealed

in the record.” United States v. James, 712 F.3d 79, 99–100 (2d Cir. 2013) (quotation

marks and citations omitted). When making that determination “we principally

consider: (1) the overall strength of the prosecution’s case; (2) the prosecutor’s

conduct with respect to the improperly admitted evidence; (3) the importance of

the wrongly admitted evidence; and (4) whether such evidence was cumulative of

other properly admitted evidence.” United States v. McCallum, 584 F.3d 471, 478

(2d Cir. 2009) (alteration and quotation marks omitted). Our Court has

16 “repeatedly held that the strength of the government’s case is the most critical

factor in assessing whether error was harmless.” Id.

Here, the government presented overwhelming direct evidence of the

defendants’ guilt. Both defendants were arrested in the act of flying cocaine into

Croatia. At trial, Cardona testified in detail about the seized shipment,

defendants’ prior drug dealings, and their involvement in the conspiracy. The

government’s evidence also came from extensive video and audio recordings of

meetings in which Landji discussed cocaine trafficking with Cardona, and which

contained multiple references to Adamu’s role in the conspiracy scheme, as well

as intercepted calls and text messages between Cardona and Fofana in which they

discussed Landji and Adamu’s participation in the conspiracy. In light of this

extensive evidence of guilt, the discrete question of whether the Šušnjar

Memorandum, if reviewed by law enforcement agents, caused the government to

question witnesses about its initial black-flight theory was inconsequential such

that we “can conclude with fair assurance that the [challenged] evidence did not

substantially influence the jury.” McCallum, 584 F.3d at 478 (quotation marks

omitted).

17 III. Cellebrite Cellphone Extractions

Next, defendants argue that the district court erred in admitting cell phone

data extracted in Croatia, and further erred in admitting the testimony of analyst

Enrique Santos, who interpreted the data and explained the process by which it

was extracted. Defendants point out that the government did not call Ante

Bakmaz, the Croatian technician who performed the extraction.

First, Landji argues that Santos’s testimony could not properly authenticate

the extracted data as required by Fed. R. Evid. 901 because he did not perform the

extraction. Second, Defendants contend that admission of Santos’ testimony

violated the Confrontation Clause. See U.S. Const. amend. VI. (“In all criminal

prosecutions, the accused shall enjoy the right . . . to be confronted with the

witnesses against him.”). We disagree.

A. Authentication of Cellebrite Extraction

Evidentiary rulings are generally reviewed for abuse of discretion. See

United States v. LaFlam, 369 F.3d 153, 155 (2d Cir. 2004). Rule 901 provides that

“[t]o satisfy the requirement of authenticating or identifying an item of evidence,

the proponent must produce evidence sufficient to support a finding that the item

is what the proponent claims it is.” Fed. R. Evid. 901(a). Rule 901 “does not erect

18 a particularly high hurdle,” and that hurdle may be cleared by “circumstantial

evidence.” United States v. Dhinsa, 243 F.3d 635, 658–59 (2d Cir. 2001). Further, the

proponent is not required “to rule out all possibilities inconsistent with

authenticity, or to prove beyond any doubt that the evidence is what it purports

to be.” United States v. Pluta, 176 F.3d 43, 49 (2d Cir. 1999). Rule 901 is satisfied “if

sufficient proof has been introduced so that a reasonable juror could find in favor

of authenticity or identification.” Id. Indeed, a document may be authenticated

by distinctive characteristics of the document itself, such as its “appearance,

contents, substance, internal patterns, or other distinctive characteristics of the

item, taken together with all the circumstances.” Fed R. Evid. 901(b)(4); see also

United States v. Maldonado-Rivera, 922 F.2d 934, 957 (2d Cir. 1990). Finally, as we

explained in SCS Communications, Inc. v. The Herrick Co., 360 F.3d 329, 344–45 (2d

Cir. 2004), the opposing party remains free to challenge the reliability of the

evidence, to minimize its importance, or to argue alternative interpretations of its

meaning, but these and similar other challenges go to the weight, not the

admissibility, of the evidence.

The government proved that the cell phones were owned by the defendants:

indeed, they admitted ownership. At trial, the government introduced evidence

19 from WhatsApp messages involving Landji, Adamu, and Fofana that included

profile photographs, account usernames, and phone numbers associated with

these messages. Santos also testified that the International Mobile Equipment

Identity (IMEI) numbers, a unique numeric identifier found on cellphones, linked

to the defendants’ cell phones and matched the IMEI numbers found on the

extraction report. Finally, Santos testified that the size of the forensic images of

the physical cellphones matched the size of the data contained in the extraction

reports, which provided additional confirmation that the data in the reports came

from the defendants’ cell phones. See App’x 1189–90. This testimony was enough

to satisfy Rule 901.

Landji’s arguments against admissibility are unpersuasive. First, he urges

that Santos could not properly authenticate the cellphone extractions because

Santos was not a “witness with knowledge” within the meaning of Rule 901(b), as

he was not present when the Cellebrite data was extracted and could not testify as

to its chain of custody. But “[b]reaks in the chain of custody do not bear upon the

admissibility of evidence, only the weight of the evidence.” United States v.

Morrison, 153 F.3d 34, 57 (2d Cir. 1998).

20 Next, Landji contends that Santos’ testimony “did not account for non-

manipulation-related defects in the data such as machine error, software glitches,

operator error, and/or omission.” Landji Opening Br. at 50. Though these

arguments may be fertile ground for cross-examination, they too bear on the

weight of the evidence, not its admissibility. See SCS Commc'ns, Inc., 360 F.3d at

344–45 (noting that challenges to reliability of evidence go to the weight of the

evidence). For these reasons, we conclude that the district court correctly

determined that the reports were sufficiently authenticated under Rule 901.

B. Confrontation Clause

Defendants also argue that the admission of the cell phone extractions

violated the Sixth Amendment’s Confrontation Clause. Specifically, they contend

that, under the Clause, they were entitled to cross-examine the Croatian technician

who conducted the extractions. In support of this contention, they primarily rely

on Melendez-Diaz v. Massachusetts, 557 U.S. 305 (2009), and Bullcoming v. New

Mexico, 564 U.S. 647 (2011), both of which involved efforts to substitute

certification or affidavits for live testimony regarding the results of a laboratory or

forensic examination. We review de novo evidentiary rulings that allege violations

of the Confrontation Clause. United States v. Vitale, 459 F.3d 190, 195 (2d Cir. 2006).

21 The Confrontation Clause bars admission of “testimonial statements” in a

criminal case where the defendant does not have the opportunity to cross-examine

the author of those statements. See Crawford v. Washington, 541 U.S. 36, 53–54

(2004). In Smith v. Arizona, the Supreme Court explained that “[t]o implicate the

Confrontation Clause, a statement must be hearsay (‘for the truth’) and it must be

testimonial—and those two issues are separate from each other.” 602 U.S. 779, 800

(2024). Smith dealt exclusively with the first point: whether a non-testifying drug

lab analyst’s report, which was relied upon by a testifying lab analyst, was

submitted for the truth. However, the Supreme Court expressly declined to

resolve what makes a statement “testimonial.” Id. at 801.

We need not opine on what makes a statement testimonial because the

cellphone extraction reports were not “statements” in the first place. Rather, they

are raw, machine-created data. Unlike the certifications or affidavits in Melendez-

Diaz and Bullcoming, the Cellebrite extraction reports do not contain attestations

or certifications by the Croatian analyst who ran the Cellebrite program because

they do not contain anything that can be characterized as an implicit or explicit

declarative statement by the examiner. That is because the Croatian examiner who

is listed on the report did not actually write it. Rather, the entire report was

22 generated through an automated process within the Cellebrite program. See

App’x 1334-41. We conclude that because the raw cellphone extraction reports

contained “only machine-generated results,” they were not the statements of

anyone. Bullcoming, 564 U.S. at 673 (Sotomayor, J., concurring in part).

But even if the cellphone extractions were admitted in error, “a reviewing

court might nonetheless say that the error was harmless beyond a reasonable

doubt.” Vitale, 459 F.3d at 195 (quoting Delaware v. Van Arsdall, 475 U.S. 673, 684

(1986)). We agree with the district court that any error in admitting this evidence

would be harmless, because the contents of the phones constituted only a small

fraction of the government’s evidence of Landji and Adamu’s involvement in the

drug conspiracy.

We have been clear that “[t]he strength of the prosecution’s case . . . is

probably the single most critical factor” in harmless-error analysis. United States v

Lee, 549 F.3d 84, 90 (2d Cir. 2008) (internal quotation marks and citation omitted).

The district court concluded here that it “view[ed] the [cellphone extraction]

evidence as quite marginal in terms of its significance to the jury,” and “believe[d]

the case [would] turn on the jury’s estimate of Mr. Cardona’s credibility.” App’x

1332. We agree. Although the cellphone extraction evidence was relevant, it

23 consisted largely of coded discussions that did not explicitly refer to criminal

activity, and the incriminating photographs and videos of airstrips and the

airplane were cumulative of Cardona’s testimony.

By contrast, the prosecution brought forth a great deal of other evidence that

both corroborated Cardona’s testimony and directly proved the defendants’ guilt.

This evidence included extensive undercover recordings of Landji’s meetings with

Cardona and Rambo, during which Landji participated in planning both his and

Adamu’s participation in the conspiracy. It also included recordings of calls

between Cardona and Fofana in which they acknowledged Landji and Adamu’s

plan to bring the test shipment of cocaine onto their G2. The jury also heard

testimony that Adamu admitted, after his arrest, that he knew Cardona and was

aware that Cardona used planes to engage in drug smuggling. See United States v.

Jean-Claude, No. (S1) 18-CR-601 (PGG), 2022 WL 2334509, at *8 (S.D.N.Y. June 27,

2022). Finally, there was evidence that Croatian law enforcement officers

recovered cocaine from the G2. Therefore, when compared to the extensive

evidence already supporting the jury’s verdict, we conclude that the admission of

the additional materials obtained from the cellphones, even if erroneous, did not

substantially influence the jury’s guilty verdict.

24 CONCLUSION

For the foregoing reasons, we AFFIRM the judgment of the district court.