Until Thursday, we had never heard the former BART officer's voice. He quit the BART force before anyone could ask him any questions publicly.
During Thursday's testimony, Mehserle said that when he shot Grant he was 6-foot-4, 6-foot-5 inches tall and weighed about 250 pounds. Today on the stand, he came across as very boyish, even nervous when he was answering his lawyer's questions. He was on the stand for about an 90 minutes, before court broke for the day.
Mehserle did not say anything about why he killed Grant, but he did talk a lot about how little Taser training he received during his time on the BART force.
New video taken by a BART passenger the night Oscar Grant was shot was released Thursday, showing a much clearer view that had never been released publicly. Prosecutors say you can see Grant on the ground with his hands behind his back, cooperating with police, before he was shot.
When Mehserle arrived at the Fruitvale station the night of the shooting, he said the noise level on the platform was so loud that he could hear the yelling when he pulled up. He did hear though dispatchers describe the suspects that police were looking for -- a description that said the group had not weapons.
Mehserle referred to Grant during his testimony as Mr. Grant. He said Grant and his friend, Jackie Bryson, appeared to be the most upset when he got to the scene, but Mehserle said he managed to calm the group down by talking to them.
One of the things Mehserle said he learned about firing a gun during his time at the police academy was to pay close attention to your surroundings. He said, "Just because you have the legal right to fire, that doesn't give you the right."
Of Officer Tony Pirone, Mehserle said, "He reminded me a lot of a drill instructor in the academy. Very hard nosed... he was very aggressive, I would say. I was probably the opposite of him."
Also released Thursday, was a cell phone picture taken by Grant showing Mehserle holding his Taser just moments before he pulled his gun out and shot Grant in the back. The picture had never before been shown outside of a courtroom.
When it came to Tasers, Mehserle said he received his training a month before the Grant shooting, and said he had actually only carried a Taser a handful of times while on duty because BART did not have enough Tasers to go around to all of the officers.
Mehserle told the jury that on New Year's Eve he was still learning how to position the Taser on his belt.
Much of the testimony that Mehserle gave Thursday was about his personal life. He said he was 28 years old, has a son who is a year and a half old, and that he was born in Germany. He reminded the court that he had just two years on the force when the incident happened.
"It was not necessary, he was not resisting, but yet they shot him in the back," said Grant's mother, Wanda Johnson, outside the courtroom Thursday. "It was murder. It was not an accident."
Mehserle will be back on the stand on Friday.