On Friday, one by one, prosecutors called to the stand all five individuals who shot their own video when Grant was killed. While their video is key to both sides in this case, what they saw with their own eyes is equally important. For one young man that memory proved to be too much.
Grants' friend Jamil Dewar broke down sobbing in a Los Angeles courtroom as he watched his own cell phone video of Grant being shot. Dewar was just 15 years old when Mehserle fired the shot that killed Grant.
Grant's uncle Cephus Johnson was in court.
"He's realizing the loss of Oscar now and it's becoming extremely painful. Though he's been suffering, he just doesn't know how much he's been suffering until now. He has to relive it, talk about it, and he has to see it," says Johnson.
In earlier testimony, Karina Vargas -- who also shot video -- told jurors Grant did not resist when officers detained him and his friends on a BART platform.
"To me it looked like he had his arms behind his back voluntarily," said Vargas.
Prosecutors claim Mehserle intentionally shot Grant. His defense says the second-year officer pulled his gun by mistake, instead of his Taser.
Vargas told the court Grant said "Don't Tase me man," two or three times in the second before he was shot.
Asked about Mehserle's reaction after the shooting, Vargas told the jury Mehserle put his hands to his head, looked "dumbfounded" and appeared to mouth the words "Oh, my God."
Tommy Cross took the stand after Vargas. He too had his camera with him and took video of the events around Grant's death. Cross also testified he saw no resistance from Grant. As for Mehserle's reaction, Cross said, "He look ed up and I looked at him and he said either 'Oh sh--' or 'Oh my God.'"
Finally, the jury saw video that appeared to show Mehserle handcuffing Grant after he had been shot.
"For the first time today, I seen Mehserle put a knee in his back, after putting a bullet hole in his back and then cuff him as if was trying to get away...and that was painful," says Johnson.
Grant died about eight hours after he was shot.
Testimony in the case will resume on Monday. It is not clear yet whether the defense intends to call Mehserle himself to the stand. He is the only one who really knows what he intended to do when he shot Grant.