Atibi Thomas went on trial Tuesday for shooting a police officer multiple times after fighting off armed robbers.

Thomas, who had no previous criminal record, has said he thought Atlanta police Officer Keith Roach, who was in full uniform and was responding to the gunfire, was one of the robbers.

“The real question is whether the jury believes a reasonable person would have believed that or did that,” Superior Court Judge Alford Dempsey told the lawyers just before jurors began hearing the case.

Roach, who survived three bullets only because of his Kevlar vest, believes Thomas belongs in prison. He was the third witness to take the stand Tuesday in the first day of testimony in the assault trial of Thomas, who faces up to 25 years in prison.

The officer testified Thomas, who had placed his pistol in his waistband after escaping the robbery, initially followed his commands and got on the ground.

“As he got on the ground he continued to look at me and he began to reach for his waistband,” Roach told the jury. “He drew his weapon. We exchanged fire and it went from there.”

According to court records, Thomas had agreed to sell four tires to Leland Cortez Sims and Darrlin Vernard Warner for $2,000 at his father’s Autotron in Lithonia and also agreed to deliver the tires to the West Wend neighborhood of Atlanta. He followed the men, but became nervous when they left I-20 seven exits before the Lee Street exit to West End. Thomas pulled off on Lee Street and stopped at a service station at the exit and phoned Sims and Warner and told them his location so they could fetch the wheels.

Thomas’ instinct was right. According to court records, Sims and Warner, intending to rob Thomas, were joined by Dontavious Marquess Berry at the West End Mall behind the service station where Thomas was waiting.

As Thomas watched Sims and Warner unload the rims, Berry pulled a gun on him. Thomas, who had a Glock .357 semi-automatic pistol that he was licensed to carry, fired first, hitting Berry in the leg. He then fled toward a Popeye’s restaurant across Oak Street, firing back at the men he feared were pursuing him.

That is when the 31-year-old Roach, who had just gotten off duty, got out of his black Tahoe on Oak Street and intervened.

Thomas said he heard Roach tell him to halt, but despite the officer’s police uniform and pointed gun, he ignored the command and ran up to the clerk at the restaurant’s window.

“I said, ‘Ma’am, I’ve been robbed. Call the police,’” Thomas said.

Roach again shouted for Thomas to get down on the ground. He complied but when the officer grabbed his wrist to handcuff him, Thomas said he saw tattoos on Roach’s arms and feared the officer was one of the robbers. He began to fight Roach.

Which man fired first is a matter of contention, but Roach’s pistol ejected the clip, leaving him unarmed. Thomas emptied his final three shots into Roach, fracturing a rib and wounding both arms. One bullet shattered a cellphone in a vest pocket above the police officer’s heart.

Roach charged at Thomas, who won the wrestling match and ended up on top of Roach, who was struggling to force Thomas’ pistol muzzle away from his face. Another witness, Donald Melvin, finally intervened and rescued the officer.

Testimony in the trial continues Wednesday.