A Dallas man who fatally shot his roommate before shooting and critically wounding a neighbor and a responding paramedic Monday was the subject of an open investigation by the FBI prior to the attack, officials say.
Officials with the Dallas FBI, police and fire departments held a news conference Tuesday morning to share the latest information into the investigation into 36-year-old Derick Lamont Brown, the man police identified as Monday's shooter, and the condition of those injured.
NBC 5 Investigates learned Monday that Brown has ties two black nationalist groups including the Dallas chapter of the New Black Panther Party and the Huey P. Newton Gun Club.
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Eric Jackson, Special Agent in Charge of the Dallas FBI, said Tuesday the bureau had an active, open investigation into Brown prior to the shooting and that they were reviewing their case file. The FBI could release no other information about their open investigation.
Dallas Assistant Police Chief Randy Blankenbaker then shared in greater detail the events as they unfolded Monday, saying Brown was acting erratically in his home that morning and that for an unknown reason he took his roommate, 67-year-old Arthur Riggings, into a back room and fatally shot him.
Brown's girlfriend, who was also in the home at the time, then ran from the home and was not injured, police said.
A neighbor, identified by police only as a 24-year-old Latin male, heard the gunshots and went outside to investigate. Police said Brown, who had gone outside, then shot his neighbor with a 7.62 caliber semi-automatic rifle.
Paramedics responding to a suicide call at about 11:30 a.m. discovered the neighbor lying in the street and stopped to provide medical care.
The paramedics quickly came under fire; paramedic William An was hit at least once and immediately collapsed to the ground. A second paramedic was able to take cover and was not injured.
Officers William Bruce Jr. and Thomas McPherson arrived at the scene at 11:36 a.m. to find the neighbor and An both collapsed in the road and critically wounded. At the same time, they came under fire and attempted to take cover, police said.
Bruce suffered a minor calf injury, possibly from bullet fragments, police said.
Moments later, officers Matthew Merta and his unnamed partner, a 1-year veteran, arrived at the location. Brown, who had retreated to his yard at this point, turned and pointed his rifle the officers. Merta's partner then fired his shotgun toward Brown.
Police believe Brown was struck by a single pellet from the shotgun blast and suffered only a minor, non life-threatening injury. He then retreated further and entered his house.
Blankenbaker said additional officers then began to arrive at the scene, including Sgt. Robert Watson and officers Christian Jackson, Gary Green, Gabriel Pina and Mathew Kalash.
"Officer Merta, Sgt. Watson and Officer Kalash placed the critically injured paramedic in the sergeant’s car and the sergeant transported him to Baylor Hospital. Officers Jackson, Green and Pina pulled the Latin male victim to safety so he could be transported to the hospital," Blankenbaker said in a statement. "Each of these events took place while the officers were still exposed to potential gunfire from the suspect. All of these officer’s actions are more than commendable and should be considered heroic."
With the wounded evacuated and the suspect believed to be barricaded inside his home, police shut down roads and blocked access to the area until the SWAT team arrived and used a robot to search Brown's home. Inside police found Brown and his roommate dead -- Brown from an apparent self-inflicted gunshot wound.
Dallas Fire-Rescue spokesman Jason Evans said Tuesday that paramedic William An is an 11-year veteran of the department. He is married and has a 3-year-old son and a second child on the way. On Tuesday, Evans said An is stable, but remains in critical condition at Baylor University Medical Center in Dallas.
"The information I have received up to this point is that he has been in and out of sleep and able to verbalize things to the medics. You know, he complained of having a lot of pain, which is completely understandable given the circumstances. He's undergone several procedures to help address the injuries from the shooting," Evans said. "At least at this juncture, as opposed to what it was yesterday, the outlook seems to be a lot more positive."
The injured neighbor remains in critical condition at Parkland Memorial Hospital in Dallas.
Blankenbaker said Brown's criminal history includes arrests for aggravated assault with a deadly weapon, possession of a controlled substance, unlawful carry of a handgun by a license holder and driving while intoxicated. Police said Brown was well-known by law enforcement because of his "excessive arrest history."
NBC 5 has learned Riggings' only criminal history is for marijuana possession.