Law360 (August 26, 2026, 4:17 PM EDT) -- The Tenth Circuit on Tuesday affirmed an Oklahoma man's murder and firearm convictions, concluding that allowing jurors to hear a missing witness's prior testimony did not violate his Sixth Amendment confrontation rights because the government made reasonable, good-faith efforts to find the witness.

Coker Dean Barker was convicted for the 2019 shooting death of Mickel Kelough in Seminole, Oklahoma, a small city within the boundaries of the Seminole Nation. Kelough was found inside his car with his head wrapped in a garbage bag and a gunshot wound to his head. Because the crime occurred in what the government defines as Indian Country, Barker was prosecuted in federal court.

Prosecutors sought to call William Lozer, who was aware of the killing, to testify. Beginning in February 2023, the government tried to locate Lozer ahead of trial, contacting his family, public defender and local law enforcement without success. They also contacted Tinker Air Force Base, his last-known location, and homeless shelters but couldn't find him.

His family and attorney said they had not heard from him in months and that he was homeless and had no phone. FBI agents also checked a possible Seminole residence and contacted several law enforcement agencies but were unable to find him.

In the lead-up to Barker's trial, prosecutors sought to admit as evidence a transcript of testimony Lozer gave during a January 2020 preliminary hearing in Barker's related state court case before it was dismissed for lack of jurisdiction.

In the testimony, Lozer said Barker asked him to act as a lookout while Barker confronted the victim. He also testified that, in a conversation that followed the murder, Barker told him about the killing and Lozer recommended that Barker "clean up the mess."

"We pretty much beat him to death. All of us did. ... We didn't rob him. Didn't take his money. He owed us," Lozer recalled Barker telling him in one of the notes he received from him while they were both incarcerated on unrelated offenses later on.

In opposing prosecutors' motion to use the testimony, Barker invoked the confrontation clause of the Sixth Amendment, which guarantees criminal defendants the right to confront their accusers in court. Barker argued the government failed to show Lozer was unavailable.

U.S. District Court Judge John F. Heil III ultimately allowed prosecutors to read Lozer's testimony and Barker's jailhouse notes to jurors, determining that attempts to summon Lozer were sufficient to show the government had made the kind of good-faith effort required under U.S. Supreme Court and Tenth Circuit precedent. The jury ultimately convicted Barker, and Judge Heil sentenced him to life in prison.

On Tuesday, a three-judge panel of the Tenth Circuit upheld Judge Heil's decision to allow the testimony and the notes, concluding that admitting the evidence did not violate Barker's confrontation rights.

"Despite the government's reasonable and good-faith efforts to locate Lozer, Lozer was unavailable for trial," U.S. Circuit Judge Nancy Louise Moritz wrote in an opinion for the panel.

Under the Supreme Court's 1980 ruling in Ohio v. Roberts, a witness is determined to be unavailable for confrontation clause purposes when the government's reasonable, "good-faith efforts," considered in the circumstances, fail to produce the witness for trial.

The appellate panel said the Tenth Circuit has never adopted a rule defining the measures prosecutors must take before a witness can be deemed unavailable. Rather, the court has recognized a series of factors it considers in making such a determination, including whether prosecutors made greater efforts in locating witnesses that are more crucial to a case or in cases involving more serious crimes.

"Applying these considerations to the facts here leads us to conclude the government acted reasonably and in good faith in searching for Lozer and nevertheless was unable to procure his presence at trial," according to the opinion.

The judges noted that while Lozer's testimony was important, other witnesses testified that Barker made incriminating statements. Barker also admitted to trying to enter Mexico a few days after Kelough's murder. And some of the incriminating jailhouse notes, known as kites, had Barker's fingerprints on them.

"No evidence indicated that Lozer was even alive in March 2023, let alone living in the Oklahoma City vicinity," according to the opinion. "Under these circumstances, the government's efforts were far from perfunctory."

A representative of the U.S. attorney's office declined to comment on the ruling Wednesday.

Counsel for Barker did not immediately respond to a request for comment.

U.S. Circuit Judges Timothy Michael Tymkovich, Michael R. Murphy and Nancy Louise Moritz sat on the panel for the Tenth Circuit.

Barker is represented by Howard A. Pincus and O. Dean Sanderford of the Office of the Federal Public Defender for the District of Colorado.

The government is represented by Linda A. Epperley, Jarrod Alan Leaman and Benjamin D. Traster of the U.S. Attorney's Office for the Eastern District of Oklahoma.

The case is U.S. v. Barker, case number 24-7100, in the U.S. Court of Appeals for the Tenth Circuit.

--Editing by Covey Son.

Update: This story has been updated to reflect the U.S. attorney's office declined to comment.

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