Update (October 8, 2019): Three suspects have been named in the murder of Joshua Brown, a witness who testified during Amber Guyger’s trial.

Avery Moore, assistant chief of the Dallas Police Department, identified Thaddeous Charles Green, Jacquerious Mitchell and Michael Diaz Mitchell as Brown’s suspected killers during a Tuesday press conference, according to The Dallas Morning News.

Moore revealed Brown’s death was the result of a drug deal gone wrong. The trio allegedly traveled from Alexandria, Louisiana, to buy drugs from Brown on Friday night.

Green and Brown had a disagreement and a physical fight ensued. Brown reportedly shot Jacquerious, and Green fired back in retaliation. Brown was found injured around 10:30 p.m. and died en route to the hospital.

After receiving “numerous tips,” Dallas Police searched Brown’s apartment, where they recovered $4,000 in cash, 12 pounds of marijuana and 149 grams of THC cartridges.

CBS News reported Jacquerious was dropped off at a local hospital and is currently in police custody. He is expected to be charged with capital murder.

Green and Michael are still at large and might have crossed state lines.

The 28-year-old, who died 10 days after he testified in Guyger’s trial, lived across the hall from Botham Jean.

Brown said in court he heard two people "meeting by surprise" on the night of Jean’s death before gunshots followed moments later.

Guyger, a former police officer, was sentenced to 10 years in prison. Moore emphasized Brown’s death had nothing to do with the trial.

Update (October 7, 2019):  Police say they are investigating Friday night’s shooting of Joshua Brown, a witness who testified for the murder of his former neighbor Botham Jean, reports CBS News.

The attorney for Jean's family, Lee Merritt, is also the attorney for Brown. 

Merritt said Brown would have been one of the first witnesses on behalf of Jean’s family in a civil case against the city of Dallas for his murder.

“To have a key witness, suddenly be killed is suspicious. Was this related to the trial? There is no clear indication,” Merritt told CBS News' Omar Villafranca.

Merritt said Brown should have been protected after he testified against former police officer Amber Guyger.

Merritt said, "if he had concerns for his safety, then the city, the county had an obligation to ensure that those concerns were met."

Brown was involved in a separate shooting incident before the trial and was fearful someone was after him.

"He had been shot less than a year ago and someone standing near him was killed," Merritt said. "He was reluctant to testify in this case because he had been shot at and he thought some people might want to do harm to him."

According to CBS News, Brown's testimony was crucial to finding Guyger guilty. 

Dallas Mayor Eric Johnson said on Twitter he believes the police will conduct a thorough investigation into Brown’s death, per Associated Press.

“Until we know more about this incident, I encourage everyone to refrain from speculation,” Johnson said.

As of Monday morning, Dallas Police said they do not have any suspects or a motive

Original: On Friday evening — just days after testifying in the case against ex-police officer Amber Guyger for the murder of his former neighbor Botham Jean — Joshua Brown was fatally shot outside of a Dallas-based apartment complex.

According to CBS Dallas-Fort Worth, the 28-year-old was reportedly attacked outside of the Atera apartments around 10:40 p.m. An anonymous government official confirmed with The Dallas Morning News that Brown endured gunshot wounds to his back and thigh.

"He was ambushed at his apartment complex as he got out of his car and shot at close range," Dallas civil rights attorney and lawyer for the Jean family Lee Merritt wrote in a Facebook post. 

"Witnesses told police they heard several gunshots and saw a silver four-door sedan speeding out of the parking lot," The Dallas Morning News reported. However, local authorities have yet to identify any possible suspects.

Brown reportedly passed away in the hospital later that night, according to NBC News.

In 2018, when Jean was shot and killed in his own home, Brown also lived in a South Side Flats apartment complex in a unit across the hallway. A witness for the prosecution in Jean's murder trial, Brown reportedly testified that he first overheard Jean singing gospel and pop songs to himself, then the sound two startled people meeting as if by surprise — presumably the exchange between then-officer Guyger and Jean that became the catalyst to the shooting. Though their words were barely audible, Brown said he eventually heard the sound of gunshots ring out from across the hall.

YouTube | The Dallas Morning News

After being found guilty for the shooting of Botham Jean, on Wednesday, October 2, Guyger was given a 10-year sentence

Now, the timing and mysterious circumstances of Brown's unexpected death has led many to allege his shooting was the result of foul play — including Brown's mother. In the same Facebook post, Merritt also said that he's been in contact with the victim's family since the incident and that Brown's mother reportedly "suspects foul play and it is difficult to rule it out."

Others online share similar sentiments. The hashtag #Justice4JoshuaBrown continues to trend on Twitter, as more details surrounding the shooting unfold.