Dallas police said Tuesday that they have identified three suspects in the fatal shooting of a key witness in the trial of Amber Guyger, the white former officer convicted of murder for killing Botham Jean, her unarmed black neighbor.

Joshua Brown was shot to death on Friday, 10 days after he testified against Guyger. The timing fueled rumors that his role in the trial had made him a target, with some alleging a conspiracy by local law enforcement.

But on Tuesday, police emphatically denied the claims and identified three suspects in the shooting, men they said who traveled from Alexandria, La., to Dallas to buy drugs from Brown and then exchanged gunfire with him when the deal went south.

“There’s been speculation and rumors that have been shared by community leaders claiming that Mr. Brown’s death was related to the Amber Guyger trial and somehow the Dallas Police Department was responsible,” Assistant Police Chief Avery Moore said at a news conference. “I assure you that is simply not true. And I encourage those leaders to be mindful of their actions moving forward because their words have jeopardized the integrity of the city of Dallas as well as the Dallas Police Department.”

Police said the suspects — Jacquerious Mitchell, 20, Michael Mitchell, 32, and Thaddeous Green, 22 — met up with the 28-year-old Brown outside his home Friday evening. Green got out of the car to talk with Brown, and the two began arguing.

Jacquerious Mitchell later told authorities that when he got out of the car too, Brown shot him in the chest. Green then returned fire, police said, hitting Brown twice in the lower body. Green grabbed Brown’s gun and backpack, and the three suspects took off, with Michael Mitchell at the wheel.

He dropped Green off at an unknown location, police said, and drove Jacquerious to a hospital, where he was later taken into custody. Michael Mitchell and Green are still at large, but police have issued warrants for their arrest. All three men will face capital murder charges.

Police searched Brown’s apartment and said they confiscated 12 pounds of marijuana, 143 grams of THC cartridges and $4,000 in cash.

The Brown family lawyer, who also represents Jean’s family, continued his calls for the Dallas department to recuse itself from the investigation. The attorney, Lee Merritt, has argued that the proximity of Brown’s killing to the Guyger trial — which led to a 10-year sentence for the former officer and raised questions about the integrity of some current members — implicates the force and undermines its credibility.

“It is important for everyone involved that this case not only be solved but the conclusions arrived to by investigators be seen as authentic and reliable,” Merritt said in a statement. “A cloud of suspicion will rest over this case until steps are taken to ensure the trustworthiness of the process.”

Merritt, who previously said that law enforcement involvement shouldn’t be ruled out, tweeted on Tuesday night that he is glad authorities believe they have identified suspects, but asked for another agency to take over the investigation “to make sure all the bases are covered due to the circumstances in this case.”

Sherrilyn Ifill, president of the NAACP Legal Defense Fund, agreed in a statement later that night.

“It is critical to public confidence in the administration of justice that witnesses who speak out against police violence are fully protected,” she said. “The suspicious circumstances of Mr. Brown’s killing should cause great alarm and demand an immediate and piercing inquiry.”

As news of the police account of Brown’s death spread, some advocates expressed doubts, particularly about the idea that the three men would make a 300-mile drive to purchase drugs.

Clint Smith, a writer and fellow at the think tank New America, called the explanation “insulting.” Radio host and political analyst Zerlina Maxwell said it is “patently ridiculous.”

Brown took the stand on the second day of the Guyger trial and wept as he described the final seconds of Jean’s life. Brown, who at the time lived in the apartment across from Jean’s, told jurors he was walking toward his unit when he overheard what sounded like a surprise meeting between Jean and Guyger.

Brown said he couldn’t make out what they were saying but said he was sure he didn’t hear Guyger shout at Jean, “Let me see your hands!” — a command Guyger said she repeated several times before shooting Jean. This testimony contradicted “a key element of the defense,” Merritt said the day after Brown was killed.

“Amber claimed she shouted commands to Botham before shooting him,” Merritt wrote on Facebook. “She didn’t. No one heard that. No neighbors. No passerby’s. Not Joshua as he walked down the corridor. No one.”

Brown ran when he heard two gunshots. Then, worried about his dog, he headed back toward his unit. Through the peephole in his door, he said, he watched Guyger pacing the hallway and talking on her phone.

“She was crying,” Brown testified during the trial. “Explaining what happened, what she thought happened. Saying she came into the wrong apartment.”

He looked down at his lap, wiped his eyes with his T-shirt and reached for a box of tissues. He said he only met Jean once, just hours before the September 2018 shooting. But Brown used to hear him across the hall, singing gospel songs and rapping Drake lyrics: “I heard him singing every morning,” he said.

Originally from Jacksonville, Fla., Brown moved to Texas in 2008. After graduating high school, he returned to Florida for college and played defensive back on the University of South Florida’s football team. After graduating, he said he moved back to Dallas and ran a company that managed Airbnb properties.

“His murder underscores the reality of the black experience in America,” Merritt said. “A former athlete turned entrepreneur — Brown lived in constant fear that he could be the next victim of gun violence, either state sanctioned or otherwise.”

Read more: