United States v. Crystal Martinez, 685 F. App'x 306

Crystal Martinez was a passenger in a vehicle crossing from Mexico to the U.S.; agents discovered ~116 kg of methamphetamine hidden in soap and fabric softener.
Driver Tina Trevino admitted she and Martinez picked up the drugs in Matamoros and that Martinez was present when drugs were shown; Trevino pleaded guilty and testified for the government.
Government sought to admit extrinsic evidence under Fed. R. Evid. 404(b): testimony that Martinez had directed her sister Diana to smuggle cash from Texas to Matamoros on multiple occasions (one arrest for $100,000).
The district court initially hesitated but admitted Diana’s testimony after an HSI agent explained that drug proceeds are commonly smuggled back to Mexico and that cash- and drug-smuggling roles often overlap; limiting instructions were given twice.
During Trevino’s testimony she volunteered that Martinez “has a lot of record”; the court sustained an objection and instructed the jury to disregard; Martinez sought a mistrial which the court denied.
Jury convicted Martinez on all counts (conspiracy/possession and conspiracy/importation of >50 g methamphetamine); Martinez appealed asserting erroneous admission of 404(b) evidence and that the court should have declared a mistrial over the prior-record remark.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Admissibility of extrinsic cash‑smuggling evidence under Rule 404(b)	Govt: evidence is admissible to prove intent/knowledge because cash smuggling is part of narcotics enterprises and makes knowledge of drug trafficking more probable	Martinez: evidence irrelevant, unduly prejudicial, and shifted burden to her to disprove knowledge	Court: Admitted evidence not an abuse of discretion — relevant to intent/knowledge; probative value outweighed prejudice given expert foundation, temporal proximity, similarity, and limiting instructions
Motion for mistrial based on witness remark about Martinez’s criminal record	Martinez: remark was prejudicial and required mistrial	Govt: remark was vague; court’s curative instruction cured any prejudice	Court: Denial of mistrial not an abuse of discretion — no substantial possibility remark affected verdict; jury presumed to follow instruction

Beechum v. United States, 582 F.2d 898 (5th Cir. 1978) (en banc) (two‑part test for admissibility of extrinsic‑offense evidence under Rule 404(b))
Kinchen v. United States, 729 F.3d 466 (5th Cir. 2013) (apply Beechum; review district court’s balancing for abuse of discretion)
Olguin v. United States, 643 F.3d 384 (5th Cir. 2011) (heightened scrutiny for Rule 404(b) evidence in criminal cases; intent is a material issue)
Sumlin v. United States, 489 F.3d 683 (5th Cir. 2007) (general abuse‑of‑discretion standard for evidentiary rulings)
Richardson v. United States, 781 F.3d 237 (5th Cir. 2015) (review of denial of mistrial for abuse of discretion)
Valles v. United States, 484 F.3d 745 (5th Cir. 2007) (reversal for mistrial only if prejudicial evidence had substantial impact)
Paul v. United States, 142 F.3d 836 (5th Cir. 1998) (limiting instruction can cure erroneous admission because jurors presumed to follow instructions)
In re Winship, 397 U.S. 358 (1970) (government bears burden to prove guilt beyond reasonable doubt)