SHAWNEE — Mike Mallinson trained Tecumseh police officer Justin Terney. Showed him the ropes. On Wednesday, the assistant chief took the witness stand and tearfully recalled the night he watched Terney lose consciousness after being shot and critically wounded by a man he chased into an area thick with cedar trees and underbrush.

"I could tell he was going blue," Mallinson testified at the trial of Byron James Shepard. "He said, 'Mike, I think I'm going out.'"

Mallinson also gave chase that night. He described clearing a barbed wire fence and hearing Terney warn the suspect to "stop or you're going to get tased again."

Next he heard gunshots.

"At that point I didn't know who was up or who was down," he testified. "I heard screaming."

Terney had been shot twice, including once in the abdomen, and was bleeding internally. Also wounded and laying near the officer was a man Mallinson identified in court as the defendant.

Prosecutors are seeking the death penalty against Shepard, 28, who is charged with first-degree murder in the March 26, 2017, killing of Terney. The defendant is also charged with knowingly concealing a stolen handgun and possession of methamphetamine.

The trial before Pottawatomie County District Judge John G. Canavan Jr. is expected to last several weeks.

Cleveland County District Attorney Greg Mashburn and his assistants are prosecuting Shepard. In his opening statement, Mashburn told jurors Shepard lied to Terney about his identity because he had a warrant out for his arrest.

"The evidence will show you that Justin Terney died that night without even knowing why he's been shot," Mashburn said. "Justin Terney died, not knowing the real name of the man that took his life that night, because this defendant didn't want to go to jail ... ."

The defendant was a passenger in a vehicle being driven by Shepard's girlfriend, Brooklyn Williams, when the officer stopped the vehicle for a defective taillight about 11:30 p.m.

Police dash cam video played for jurors Wednesday showed the traffic stop. Williams is seen speaking to Terney, and Shepard tells the officer his name is James Bishop, Mashburn told jurors.

The two make small talk while the dispatcher searches for the false identity. After it becomes apparent Shepard is lying, Terney asks him again to be honest. Shepard turns his back on Terney before fleeing into a wooded area off the side of the road.

The officer's microphone picks up Terney screaming at Shepard to stop. Then the sound of gunfire is heard on the dash cam video. "Central, I've been hit," Terney said. The officer, who had been on the job about 200 days, died at OU Medical Center the next day.

Defense attorney Shea Smith told jurors Terney's death was "not intentional."

"Byron Shepard had a warrant out for his arrest. And he did lie to the officer," Smith said. "You'll see the video. You'll see that for over three minutes, Byron Shepard stood next to that police car and talked to that officer. The entire time that he was doing that he had the gun on him. Never did he take that gun out and try to shoot the officer. If he wanted to kill him, he had plenty of time."