Updated at 6:12 a.m. Wednesday: Revised to note that the second of three suspects has been arrested.

After days of speculation surrounding the shooting of Joshua Brown, a witness in the Amber Guyger trial, Dallas police identified three suspects Tuesday in connection with Brown's death.

Tuesday evening, NBC News reported that the second of the three, Michael Diaz Mitchell, had been taken into custody in Louisiana. Dallas police later confirmed that he had been taken into custody by U.S. marshals in Marksville, La.

Earlier that day, Assistant Chief Avery Moore said that one of the suspects, Jacquerious Mitchell, 20, was in custody at Parkland Hospital.

During that news conference, held at Dallas police headquarters, officials said Brown was fatally shot Friday in a drug deal gone bad at an apartment complex on Cedar Springs Road. All three suspects came from Alexandria, La., to purchase drugs from him, police said.

The third suspect, Thaddeous Charles Green, 22, remains at large.

The announcement of the suspects' names came as pressure increased from community leaders for an independent investigation into Brown's case. Brown had testified in the murder trial of Guyger, a former Dallas police officer convicted of murder last week and sentenced to 10 years in prison.

The timing of Brown's death raised public speculation about whether the shooting was somehow tied to his testimony.

Brown's family declined a request for an interview through civil rights attorney Lee Merritt on Tuesday but said in a statement the department should not continue to lead this investigation. The statement did not refute any details from police officials.

"A cloud of suspicion will rest over this case until steps are taken to ensure the trustworthiness of the process," the family said in a written statement.

Dallas Assistant Chief of Police Avery Moore takes a moment to himself as he offers condolences to Joshua Brown's family during a news conference about his death. Brown was killed in a drug deal gone bad. (Tom Fox / Staff Photographer)

Moore gave condolences to the Brown family and said the department was working "diligently" to find the remaining suspects. Moore then addressed the conspiracy theories and said they "simply are not true."

Without pointing to specific statements, he issued a warning to community leaders.

"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," he said.

According to police, the three suspects were in the same car when they arrived at Brown's apartment complex Friday night. Green got out of the car to talk to Brown, which led to an altercation between the two men. Jacquerious Mitchell told police that when he got out of the car, Brown shot him first.

Police on Tuesday identified Thaddeous Charles Green, 22, as one of the three suspects wanted in connection with the death of Joshua Brown. (Courtesy of DPD)

Jacquerious Mitchell also told police he heard two more gunshots as he lay inside the vehicle.

Green took Brown's backpack and gun, police said. Michael Mitchell was the driver and dropped off Green at an unknown location. Michael Mitchell then dropped off Jacquerious, who is his nephew, at the hospital.

Officers were called Friday night to the Atera apartments in the 4600 block of Cedar Springs Road, where witnesses reported hearing gunshots and seeing a silver four-door sedan speed out of the parking lot.

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

The shooting occurred about 3.5 miles from the South Side Flats complex in the Cedars, where Brown had lived across the hall from Botham Jean, the black neighbor Guyger shot as he sat in his apartment. Guyger, a white officer, was off duty when the shooting occurred and said she had mistaken Jean’s apartment for her own.

The department confirmed Sunday afternoon that Brown was the victim officers found around 10:30 p.m. Friday with multiple gunshot wounds to his lower body. Brown died after being taken to Parkland Memorial Hospital.

Brown was also connected to a shooting last year at a strip club in northwest Dallas that left a 26-year-old man dead.

According to an affidavit, a man had waited for Brown outside Dallas Cabaret and fought him when he came out. When Brown tried to leave, the man started shooting, killing Nicholas Shaq'uan Diggs, 26, and injuring Brown.

But police on Tuesday said they did not have evidence that the three suspects were connected to that incident.

Brown's death has prompted response from local and national public officials, including some presidential candidates.

Police on Tuesday identified Michael Diaz Mitchell, 32, as one of the three suspects wanted in connection with the death of Joshua Brown. (Courtesy of DPD)

Mayor Eric Johnson had urged patience after Brown's death shocked the city. In a statement Tuesday, Johnson applauded the efforts by Dallas detectives.

"I want to thank everyone who demonstrated patience and responsibly reserved their judgment while the Dallas Police Department gathered the facts regarding the death of Joshua Brown. I urge anyone with additional information about this case to come forward," Johnson said in a statement.

Before the news conference Tuesday, state District Judge Tammy Kemp, who presided over Guyger's trial, said in an interview she was shocked to learn of his death and deeply saddened for his family.

"I just can't imagine what his parents might be going through, and I hate that for them," Kemp said. "I really hate that for them."

Kemp recalled how Brown was visibly moved during the testimony he gave during Guyger's murder trial.

During the trial, Brown testified about the night Jean, who lived across the hall from him, was shot.

He told the jury how he had returned home after watching a football game at a bar the night of Sept. 6, 2018.

Standing in the hallway, he heard what sounded like "two people meeting by surprise," followed by gunfire.

Brown got emotional when he recounted that he hadn't met Jean before that day -- they were both visited by the leasing office about a noise complaint -- but he often heard his neighbor sing gospel music and Drake.

Brown, 28, had played football at the University of South Florida. He was from Jacksonville, Fla., and had worked managing Airbnbs before his death.

How to contact police about the case

Anyone with information about the shooting may contact Detective Jacob White at 214-671-3690 or email jacob.white@dallascityhall.com and refer to the case number, 202433-2019.

Crime Stoppers will pay up to $5,000 for information leading to an arrest and indictment in this case. To make an anonymous tip, call 214-373-8477.

Bill Perkins, an author and the CEO of the BrisaMax Holdings consulting firm, is offering a $100,000 reward to find who killed Brown, civil rights activist Shaun King announced Sunday

Staff writer Dana Branham contributed to this report.