ATLANTA - (AP) A former Atlanta police officer on trial for a botched drug raid that led to the death of a 92-year-old woman said Wednesday he went along with a cover-up because he felt threatened by his fellow officers.

Kathryn Johnston was shot 39 times as plainclothes narcotics officers busted into her house using a "no-knock" warrant on Nov. 26, 2006. During nearly eight hours of testimony, Arthur Tester said he was instructed by two other officers after the shooting to memorize a cover-up story that they had witnessed an informant buying drugs at Johnston's home.

Tester also told the jury in Fulton County Superior Court that he didn't know officer Jason R. Smith had lied to a judge to get the warrant and then planted drugs in Johnston's basement to back up the story. In his often tearful testimony, Tester said he eventually decided to cooperate with federal investigators because he "couldn't take it anymore."

"A woman was dead and they were trying to implicate me in their story," Tester said. "I didn't lay a hand on this woman. I wanted nothing to do with it."

Prosecutors say Tester had opportunities to tell the truth but decided to do so only when federal agents told him they knew he was lying.

Tester was in the backyard of Johnston's home during the raid, during which Johnston fired one shot from a pistol as police were breaking down her door. She did not hit any of the officers.

Fulton County prosecutor Kelly S. Hill has said even though Tester never fired a shot, he shared responsibility for Johnston's death because he went along with a lie.

The Rev. Al Sharpton, who was sitting in the courtroom during the morning, called Tester's testimony "chilling" and the shooting "a complete disregard for the criminal justice system."

Tesler is charged with lying in an official investigation, violating his oath as an officer and false imprisonment. The trial is likely to be the only one in the Johnston shooting because former officers Gregg Junnier and Smith have already pleaded guilty to state manslaughter and federal civil rights charges. Junnier testified against Tesler last week.

The fatal shooting led to sharp criticism of the police department, and a shake-up of the narcotics unit, which Tester's attorney, William McKenney, has said routinely planted drugs and lied to obtain search warrants. It also prompted a review of how officers obtain and use no-knock warrants, which are intended to keep drug suspects from having time to destroy evidence.

Closing arguments are expected to begin Thursday morning.