UPDATE: A second suspect, Michael Mitchell, was arrested Tuesday in Louisiana.

DALLAS (CBSDFW.COM) – Dallas Police have arrested a suspect and identified two others in the Joshua Brown capital murder case.

Brown, a witness in the Amber Guyger murder trial, was shot and killed last Friday during a drug deal.

Jacquerious Mitchell, 20, will be charged with capital murder, police said during a news conference Tuesday afternoon.

Mitchell, who was seriously wounded and currently being treated at Parkland Hospital, is a suspect along with two fugitives, Thaddeous Charles Green, 22, and Michael Diaz Mitchell, 32, who left the state.

Police are pursuing them for capital murder charges as well.

The trio came from Alexandria, Louisiana to purchase drugs from Joshua Brown, Assistant Chief Avery Moore said.

“Thaddeous Green was the facilitator. He’s the one who contacted Joshua Brown,” Asst. Moore said.

Moore said when they got to the location, “Green gets out of the vehicle, has a conversation with Joshua Brown which escalates into physical altercations.”

Jacquerious Mitchell told police when he got out of the vehicle, Brown ordered him to get back in his vehicle and shot him in the chest, Asst. Chief Moore said.

Jacquerious Mitchell said while wounded in the vehicle, he heard two more gun shots.

“He said that Thaddeous Green shot Joshua Brown two times,” Asst. Chief Moore said.

Green also took Brown’s backpack and gun.

Michael Mitchell was the driver.

Police said he dropped Green off to an unknown location and took Jacquarious to the hospital. He is currently in police custody at Parkland Hospital.

Police also executed a search warrant at Brown’s apartment where they confiscated 12 pounds of marijuana, 143 grams of THC, cartridges and $4,000 in cash.

WATCH DALLAS POLICE NEWS CONFERENCE HERE

Dallas Mayor Eric Johnson released the following statement on the investigation:

“I am grateful that our detectives have taken the initial steps necessary to bring closure to this case. 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.”

Almost a year before testifying in Amber Guyger murder trial, Brown was wounded in a shooting outside Dallas Cabaret South, a strip club off Interstate-35, that left another man dead.

Brown believed he was the target in the November 23, 2018 strip club shooting and felt there were “still people out there who wanted to do him harm,” according to attorney Lee Merritt, who represents Brown’s family.

Merritt says Brown’s family wants Dallas Police to turn over the investigation into Brown’s death to another agency.

His murder happened just 10 days after he testified in the Guyger case.

Brown lived on the same floor as Botham Jean at the South Side Flats and he testified that on the night Jean was killed, he heard what sounded like “two people meeting by surprise” and then two gunshots.