United States v. Shaughnessy

CourtCourt of Appeals for the Fifth Circuit
DecidedOctober 2, 2025
Docket24-10126
StatusPublished

This text of United States v. Shaughnessy (United States v. Shaughnessy) is published on Counsel Stack Legal Research, covering Court of Appeals for the Fifth Circuit primary law. Counsel Stack provides free access to over 12 million legal documents including statutes, case law, regulations, and constitutions.

Bluebook
United States v. Shaughnessy, (5th Cir. 2025).

Opinion

Case: 24-10126 Document: 84-1 Page: 1 Date Filed: 10/02/2025

United States Court of Appeals for the Fifth Circuit ____________ United States Court of Appeals Fifth Circuit

FILED No. 24-10126 October 2, 2025 ____________ Lyle W. Cayce United States of America, Clerk

Plaintiff—Appellee,

versus

Sean Shaughnessy,

Defendant—Appellant. ______________________________

Appeal from the United States District Court for the Northern District of Texas USDC No. 3:19-CR-189-1 ______________________________

Before Stewart, Dennis, and Haynes, Circuit Judges. Per Curiam: Sean Shaughnessy appeals his conviction and sentence following a jury’s verdict finding him guilty of two drug-conspiracy counts, one distribution count, and one possession of child pornography count, all arising from his use of online dark web marketplaces to traffic narcotics. He challenges the sufficiency of the evidence supporting his conspiracy convictions, the admission of certain trial evidence, and the application of a sentencing enhancement. For the reasons that follow, we AFFIRM. Case: 24-10126 Document: 84-1 Page: 2 Date Filed: 10/02/2025

No. 24-10126

I Shaughnessy’s convictions stem from a multi-year federal investigation into a digital drug-trafficking enterprise he ran on the “dark web.” The dark web is a concealed segment of the internet that requires special software to access and masks users’ identities and locations through layers of encryption. Within that hidden network, Shaughnessy maintained pseudonymous vendor accounts on multiple “dark web marketplaces” (DWMs). There, he advertised, sold, and shipped controlled substances and analogues to buyers nationwide and accepted payment in the cryptocurrency Bitcoin 1 to preserve anonymity, which he converted to cash through unregulated avenues that avoided identity verification. Between 2016 and 2019, federal and state investigators conducted searches of Shaughnessy’s residences and related surveillance that yielded a cohesive body of evidence tying him to this scheme, including: seizures of narcotics and shipping supplies; handwritten and digital ledgers detailing orders, pseudonyms, addresses, and payments; intercepted international parcels to his post office box; undercover Bitcoin-to-cash exchanges; and forensic examinations of his computers linking the conduct to his accounts and revealing an encrypted folder containing child pornography. A Shaughnessy’s involvement with the dark web drew law-enforcement attention in July 2016, when Irving, Texas police officers arrested him at a Motel 6 on an unrelated warrant. During the arrest, officers observed white powder beneath Shaughnessy’s nostrils and saw him drop a bag of white powder. A field test presumptively indicated the bag contained _____________________ 1 We have previously detailed the function and use of the cryptocurrency Bitcoin. See United States v. Gratkowski, 964 F.3d 307, 309 (5th Cir. 2020).

2 Case: 24-10126 Document: 84-1 Page: 3 Date Filed: 10/02/2025

approximately 15.1 grams of cocaine. Officers then obtained a warrant to search the room and Shaughnessy’s vehicle. The search uncovered 462 additional grams of suspected cocaine, digital scales, unused plastic baggies, numerous postal shipping labels, tracking slips, and mailing envelopes addressed to various recipients. Officers also recovered handwritten ledgers that investigators would later determine detailed Shaughnessy’s use of multiple DWMs to distribute narcotics, listing usernames, customer addresses, quantities sold, payment records, and shopping lists for drugs including fentanyl and pentedrone. A Texas grand jury indicted Shaughnessy on one court of possession with intent to distribute cocaine. 2 However, laboratory analysis by the Southwestern Institute of Forensic Sciences (SWIFS) failed to identify most of the seized powders, save for 2.8 grams of a mixture it determined contained cocaine, pentedrone, and other substances. Shaughnessy pleaded guilty to attempted possession of a cocaine and, on August 11, 2017, the state court sentenced him to 90-days’ imprisonment, but he was released the same day after crediting time served. That same month, undercover federal agents encountered Shaughnessy when he sought to liquidate Bitcoin later traced to his narcotics sales. After failing to cash out his Bitcoin through a regulated cryptocurrency exchange that required documentation he could not provide, Shaughnessy turned to “Gold,” another dark web vendor who anonymously mailed U.S. currency in exchange for Bitcoin and charged substantially higher fees than traditional exchanges. Unbeknownst to Shaughnessy, Gold was cooperating with federal authorities, and Homeland Security Investigations Special Agent Jason Samuels had assumed control of the account. Between August and

_____________________ 2 See Texas v. Shaughnessy, No. F-16-34034 (Tex. Dist. Ct. Aug. 30, 2016).

3 Case: 24-10126 Document: 84-1 Page: 4 Date Filed: 10/02/2025

October 2017, Agent Samuels recorded roughly $150,000 in Bitcoin-to-cash transactions with Shaughnessy. Agents also intercepted one package and met Shaughnessy in person, at which point he declined to explain the source of the funds or identify his occupation. The investigation continued over the following months. In November 2017, SWIFS reexamined the substances seized during the July 2016 search of Shaughnessy’s motel room. Their analysis concluded that the 15.1 and 462 grams of suspected cocaine were the controlled substance analogue N- ethylhexedrone. 3 In March and April 2018, U.S. Customs and Border Protection intercepted two international packages addressed to a post office box in Addison, Texas belonging to Shaughnessy. Each package originated in China and contained large quantities of N-ethylhexedrone—941 grams in one and 49 grams in the other. Postal records showed that the same box had received at least eleven international shipments from China and Hong Kong. A month later, in May 2018, federal agents and local officers executed a search warrant at Shaughnessy’s residence in Irving, Texas. Inside a bedroom safe, they found 246.8 grams of N-ethylhexedrone and 84.7 grams of FUB-144, another controlled substance analogue. 4 Agents also recovered additional drug paraphernalia and a laptop. A forensic review of the laptop uncovered a text file containing another detailed ledger of narcotics transactions, including product names, dates, quantities, shipping addresses, and references to DWM platforms. The same review linked Shaughnessy to

_____________________ 3 N-ethylhexedrone is an analogue of the controlled substance pentedrone, both synthetic cathinones. Synthetic cathinones are a class of stimulants commonly marketed as “bath salts.” 4 FUB-144 is a synthetic cannabinoid and classified as a Schedule I controlled substance analogue. See Temporary Placement of FUB-144 into Schedule I, 84 C.F.R. § 15505 (2019); Placement of FUB-144 into Schedule I, 87 C.F.R. § 20318 (2022).

4 Case: 24-10126 Document: 84-1 Page: 5 Date Filed: 10/02/2025

the email address “Fent4U@safemail.net,” a moniker also found in DWM user profiles. Agents arrested Shaughnessy based on an outstanding warrant in Texas, but he was released on bond. Agents traced several shipments listed in Shaughnessy’s ledgers to his customers in Texas. Two individuals—Jennifer Greer and Britt Osbourn— later testified that they had purchased fentanyl and fentanyl analogues from Shaughnessy through the DWMs “Dream” and “Trade Route.” A third recipient, Darrell Hawk, died in November 2017 from an overdose involving methoxyacetyl fentanyl (MAF) 5 shortly after receiving a package mailed by Shaughnessy. In each case, the transaction details were corroborated by entries in Shaughnessy’s ledgers.

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United States v. Shaughnessy, Counsel Stack Legal Research, https://law.counselstack.com/opinion/united-states-v-shaughnessy-ca5-2025.