Three suspects have been identified in the murder of Joshua Brown, a key witness in the murder trial of former Dallas police officer Amber Guyger.

Jacquerious Mitchell, 20; Michael Mitchell, 32; and Thaddeous Green, 22, traveled from Alexandria, Louisiana, to purchase drugs from Brown, according to authorities.

Jacquerious Mitchell is in custody and the other two are being sought, Dallas Assistant Police Chief Avery Moore said at a news conference Tuesday.

Thaddeous Charles Green is accused of shooting Brown two times, Moore said. On the night of the shooting, Green had a conversation with Brown that escalated into an argument.

Brown, 28, was found lying on the ground in an apartment parking lot with multiple gunshot wounds, two days after Guyger was convicted of murder.

Brown’s slaying occurred less than six miles from the apartment complex where Jean was fatally shot by Guyger on Sept. 6, 2018. Brown, who was killed Friday, testified in Guyger’s murder trial about the September 2018 night that she fatally shot Botham Jean, who was his neighbor.

Brown had lived across the hall from Jean, 26, at the Southside Flats apartment building in Dallas.

Guyger, who lived a floor below Jean, testified she mistakenly entered his apartment instead of her own.

She was sentenced to 10 years in prison.

This is a developing story. Check back for updates.