In an emotional courtroom session, Johannes Mehserle broke down in tears as he told jurors in his murder trial that he heard a pop and thought the Taser had malfunctioned.
"I remember the pop that wasn't very loud. It wasn't like a gunshot. I remember wondering what went wrong with the Taser. I thought it malfunctioned," he said.
Mehserle, who is white, has pleaded not guilty to murdering 22-year-old Oscar Grant on New Year's Day 2009.
The trial was moved to Los Angeles from Alameda County because of intense media coverage and racial tensions.
Mehserle resigned shortly after the shooting.
Mehserle's mother also was in the courtroom and sobbed.
Mehserle, 28, had maintained a public silence for 18 months about what led him to shoot Grant until he took the witness stand in a surprise move Thursday.
On direct examination by his attorney Michael Rains, Mehserle told jurors that he struggled to restrain Grant while he was on his stomach and repeatedly told him, "Give me your hands." Mehserle testified that he saw Grant putting his right hand into his right pocket.
"I made a decision at that point to tase him," Mehserle said. "It made me question what his intentions were." After he fired the handgun, Mehserle said he was in disbelief at what had just happened. He said he heard a lot of yelling, presumably from Grant's friends and a crowded train of onlookers, some of who took video of the shooting.
"I remember Mr. Grant saying, 'You shot me,' " Mehserle recalled.
Prosecutors say Mehserle intended to shoot Grant, and that Mehserle used his handgun because officers were losing control of the situation. Mehserle wore his stun gun on his front left side the night of the shooting, while his handgun was mounted on his right hip.
On cross-examination, Alameda County Deputy District Attorney David Stein poked holes in the defense's contention that poor training may have contributed to Mehserle's confusion during the shooting. Mehserle received a minimum six hours of stun gun training while he was employed at BART.
Stein asked Mehserle if he felt he was ill-prepared to be a BART police officer.
"No, sir," Mehserle said.
