"There is no excuse for his behavior. There is no excuse," said Oscar Grant's mother Wanda Johnson.
Johnson says Officer Tony Pirone was the aggressor in the New Year's shooting of her son by a BART police officer.
But Pirone testified for the first time, saying the young men detained on the Fruitvale platform resisted arrest. One cursed, refused to sit down and told Pirone he wasn't a real police officer because he's a BART cop.
When asked who that person was, Pirone looked directly at Grant's family sitting in the front row of the courtroom and said Oscar Grant III.
"He was the overly aggressive officer. But for him, none of this never would have happened," said Grant family attorney John Burris.
BART officer Marysol Domenici also took the stand. Along with Pirone, she was the first to respond to the call that morning. She too said Grant resisted, but when asked to point out the video showing it, she couldn't.
Prosecutor David Stein accused Domenici of exaggerating her testimony to justify the shooting. He told her: "you're saying it now to make it appear that Oscar Grant was more aggressive than he was, isn't that true?"
Domenici said even now, she has no regrets about what happened.
Asked if the shooting was Grant's fault, she told the court: "If he would have just stayed seated he would have been fine. But he didn't listen."
After former BART officer Johannes Mehserle fired the fatal shot, Domenici said the situation got so chaotic, she thought she too might have to fire her gun and use lethal force.
"If you look objectively at that video, and I think most responsible people would say 'why are you thinking about deadly force?' It didn't seem appropriate," said legal analyst Michael Cardoza.
Legal experts say there's already been enough evidence presented in this proceeding for this case to go to trial. Nonetheless, Pirone will be back on the stand on Wednesday to continue his testimony.