SAN FRANCISCO — Sgt. Brandon Davis vividly recalled the moment before he killed Eric Wayne Berry, but it was not the way it really happened.

“I told him to drop his weapon, twice,” the police officer then in Fort Smith, Ark., said. But after repeated viewings of a video of the shooting, captured by a minicamera he was wearing, he said, “it turned out it was nine different times. He kept telling me to drop my weapon.” When Mr. Berry raised his .45-caliber pistol on the officer and leaned at an angle that could improve his marksmanship, Sergeant Davis said, he shot Mr. Berry in the heart.

The shooting, tragedy that it was, was speedily cleared by his superiors because the entire incident was captured on tape. “It happened at noon on a Wednesday,” Sergeant Davis said. “I first watched it with the police psychiatrist on Thursday morning. I got out of there and I was cleared for work.” He has watched it many times since then, to shed any lingering doubts about his course of action.

Sergeant Davis, who now works on the police force in nearby Greenwood, was testing a new kind of camera, to be worn by an officer, when his fatal encounter was recorded in November 2009. Since then, both the hardware and software in the system have been significantly modified by Taser International, the maker of the camera. Taser is better known for stun guns that deliver a painful and immobilizing electric shock.