86 F.4th 332
6th Cir.2023Background
- Two young men (Allen McAllister and Brett Dame) fatally overdosed on August 20–24, 2019; medical examiners found fentanyl (and heroin in Dame) as but-for causes of death.
- Investigators linked both victims to Mustafa Reynolds by phone records and witness testimony (including co-user/dealer Dan Errico) showing drug transactions at times/places consistent with Reynolds’s sales.
- Police used an undercover detective to buy two baggies from Reynolds; lab testing showed fentanyl-heroin mixtures (one baggy fentanyl-dominant, one roughly equal mix).
- The government introduced cellphone-location evidence mapped with a commercial tool called TraX (Wi‑Fi, Verizon RTT arcs, and antenna-coverage maps) and expert testimony from Detective Heikkila about phone locations.
- Reynolds was convicted on three distribution counts (two death‑result enhancements) and sentenced to 328 months; he appealed raising four claims: insufficiency of evidence on death‑results; Daubert challenge to TraX antenna maps; exclusion of Errico’s post‑overdose texts; and alleged prosecutorial vouching.
Issues
| Issue | Plaintiff's Argument (United States) | Defendant's Argument (Reynolds) | Held |
|---|---|---|---|
| Sufficiency of evidence that Reynolds’s sales were the drugs that caused victims’ deaths | Evidence (texts, Wi‑Fi/RTT/cell‑site data, Errico’s testimony, undercover buy) supports a reasonable jury finding the specific fentanyl‑heroin mixtures came from Reynolds and were but‑for causes | Gap in the proof: time elapsed and possible intervening sources mean no rational trier could link Reynolds’s specific sales to the deaths | Affirmed — sufficiency met; jury reasonably could find the sold mixtures were the same drugs that caused death (Burrage/Davis standard) |
| Daubert challenge to TraX antenna‑coverage mapping | TraX is a visualization tool; its amoeba‑shaped, conservatively large coverage areas are testable, widely used in law enforcement, have a low relevant error rate for locating whether a phone fell inside the shaded area | TraX’s shape and proprietary sizing algorithm lack peer review, have no published validation, and therefore are unreliable under Daubert/Kumho | Affirmed — district court did not abuse discretion; TraX admissible for general location because maps were conservative, testable, and the relevant location‑accuracy error rate supported reliability |
| Exclusion of Errico’s August 23–27 text messages (defense theory: alternate source like fentanyl‑laced Xanax or Dee sold the purple heroin) | Texts were remote, speculative, and offered at best marginal relevance to who supplied the fatal drugs | Exclusion violated Reynolds’s constitutional right to present a complete defense; texts could raise reasonable doubt | Affirmed — no constitutional violation; exclusion under Rule 401 was not arbitrary or disproportionate and texts would not have created reasonable doubt beyond admitted evidence |
| Prosecutorial vouching during closing (statements about Errico’s credibility/motive) | Prosecutor’s comments merely pointed to evidence explaining why jury could credit Errico (no promises, cooperation motive, admitted crimes) | Prosecutor improperly vouched for Errico, implying government belief in his truthfulness | Affirmed — remarks were evidence‑rooted rehabilitation, not improper personal vouching or reliance on facts outside the record |
Key Cases Cited
- Daubert v. Merrell Dow Pharm., 509 U.S. 579 (1993) (benchmarks for admissibility of expert testimony under Rule 702)
- Kumho Tire Co. v. Carmichael, 526 U.S. 137 (1999) (Daubert principles apply to all expert technical testimony)
- Burrage v. United States, 571 U.S. 204 (2014) (death‑results enhancement requires but‑for causation)
- Davis v. United States, 970 F.3d 650 (6th Cir. 2020) (statutory death‑results enhancement applies when the defendant’s drugs are the same drugs that caused death)
- Carpenter v. United States, 138 S. Ct. 2206 (2018) (cellsite/cellphone location principles and privacy context)
- Holmes v. South Carolina, 547 U.S. 319 (2006) (limits on exclusion of defense evidence; standard for arbitrary exclusion)
- Crane v. Kentucky, 476 U.S. 683 (1986) (right to present a complete defense)
- United States v. Gissantaner, 990 F.3d 457 (6th Cir. 2021) (standard of review for admissibility decisions)
- United States v. Jeffries, 958 F.3d 517 (6th Cir. 2020) (interpretation of §841(b)(1)(C) death‑results enhancement)
- United States v. Potter, 927 F.3d 446 (6th Cir. 2019) (sufficiency review framework)