UNITED STATES COURT OF APPEALS FOR THE SIXTH CIRCUIT

┐ UNITED STATES OF AMERICA, │ Plaintiff-Appellee, │ > No. 22-1431 │ v. │ │ MUSTAFA DEVILLE REYNOLDS, │ Defendant-Appellant. │ ┘

Appeal from the United States District Court for the Western District of Michigan at Grand Rapids. No. 1:20-cr-00024-1—Paul Lewis Maloney, District Judge.

Argued: July 26, 2023

Decided and Filed: November 9, 2023

Before: McKEAGUE, GRIFFIN, and MURPHY, Circuit Judges. _________________

COUNSEL ARGUED: Dennis Belli, Columbus, Ohio, for Appellant. Daniel T. McGraw, UNITED STATES ATTORNEY’S OFFICE, Grand Rapids, Michigan, for Appellee. ON BRIEF: Dennis Belli, Columbus, Ohio, for Appellant. Daniel T. McGraw, UNITED STATES ATTORNEY’S OFFICE, Grand Rapids, Michigan, for Appellee. _________________

OPINION _________________

MURPHY, Circuit Judge. A jury convicted Mustafa Reynolds of selling a fentanyl-heroin mixture that killed two young men. Investigators connected Reynolds to these fatal drugs in part through cellphone records, including records showing the general locations of several phones. Reynolds now raises four issues on appeal. First, he argues that the government introduced No. 22-1431 United States v. Reynolds Page 2

insufficient evidence to convict him. Second, he argues that a government expert identified the phones’ general locations using a software program that flunks the reliability standards from Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993). Third, he argues that the district court violated the Constitution by excluding text messages that allegedly supported his innocence. And lastly, he argues that the prosecutor improperly “vouched” for a key government witness during closing arguments. Disagreeing on all fronts, we affirm.

I

This case comes to us after Reynolds’s criminal trial. So our summary of the facts will resolve any evidentiary conflicts in the light most favorable to the jury’s guilty verdict. See United States v. Maya, 966 F.3d 493, 496 (6th Cir. 2020).

Allen McAllister and Brett Dame were close friends who lived in Grand Rapids, Michigan. They met while forming their band and still performed together years later in the summer of 2019. McAllister played the drums; Dame played lead guitar. Apart from their shared love of music, they also struggled with a shared heroin addiction. Sadly, on the night of August 20, 2019, the young men fatally overdosed on drugs that they had separately obtained from the same source: Reynolds.

Before that night, McAllister and Dame had learned of Reynolds from a heroin addict named Dan Errico. Errico bought heroin from a few dealers, including Reynolds. According to Errico, Reynolds had “pretty good” and “consistent” heroin. Errico Tr., R.173, PageID 1810. Reynolds usually sold drugs to his customers behind a local store close to Errico’s Grand Rapids home.

After meeting at a deli where they worked, McAllister and Errico even