A white former South Carolina policeman testified in his murder trial on Tuesday that he felt "total fear" before shooting and killing an unarmed black man last year in an incident that intensified debate about racial bias in law enforcement.

The testimony by Michael Slager, 35, marked his first detailed public account of the April 2015 death of motorist Walter Scott, 50, in North Charleston. A bystander's cellphone video appeared to show Slager firing at Scott's back as he fled.

Slager, dressed in a dark suit as he spoke from the witness stand in a Charleston courtroom, described how a normal Saturday turned deadly after he stopped Scott for a broken brake light.

Slager said he was going to write Scott a warning, but the motorist ran from him, according to an account of the testimony from WCIV television. The live streaming video from court briefly went down Tuesday morning while Slager spoke.

Slager testified that when he attempted to use a Taser to subdue Scott they ended up in a scuffle. Slager said Scott gained control of his stun gun, the TV station reported on its website.

"In my mind, fear. I was scared," Slager said, describing Scott as coming at him. "It was total fear that Mr. Scott didn't stop."

Then Slager said he pulled out his gun and opened fire.

"When you shot him, were you filled with ill will or a depraved heart?" defense attorney Andy Savage asked earlier Tuesday.

"No, I was not," Slager said.

The account by Slager, who was dismissed from the North Charleston Police Department after the shooting, offered a different view of the incident than what state prosecutors argue was captured by the bystander's footage of the incident.

They contend Slager did not appear to be in any danger when he hit Scott with five shots. Prosecutors presented the video to the jury of 11 whites and one black during the trial, now in its third week, and played portions during Slager's cross-examination.

The state said Scott fled because he was behind on child support payments and feared he would be arrested during a routine check.

Prosecutors have accused Slager of altering the crime scene by moving the Taser closer to the handcuffed body so he could claim Scott had taken the stun gun.

Slager faces a maximum of life in prison if convicted.

(Reporting by Letitia Stein in Tampa, Fla.; Editing by Colleen Jenkins and Jeffrey Benkoe)