Eyewitness testimony in the trial of an accused killer is providing new information about the events surrounding the death of Cori Baker.
Marquis Bullock is now on trial in the Tulsa County District Court.
He’s accused of killing 13-year-old Cori Baker.
Baker when missing from Union Alternative High School in November of 2007 and months later her body was discovered at a Creek County paintball park.
Prosecutors say Bullock was the last person seen with Baker when she left school.
FOX23’s Abbie Alford was in the courtroom for the first day of testimony.
On Thursday ten witnesses took the stand. Including a man who says he could have kept Baker alive had he just called police.
Not long after 13-year-old Cori Baker went missing, her picture was seen everywhere, her family pleaded for her return.
“Will you just please, please, please, please, if you're watching this just please tell me where my sister is,” says Courtney Baker in November 2007.
However, when Marquis Bullock surfaced as the suspected killer, Buddy Sherrill says he couldn’t forget that face.
"When I saw the picture of him I knew immediately that is who I had seen because I got a very good look at him," says Sherrill.
In court, Sherrill testified that on the very day Baker disappeared he’d seen her and Bullock in the suspect’s red Firebird near 71st and Riverside. Sherill said it looked like they were arguing.
"I can remember Cori's look when she came up beside us and I should have done something. I just should have. I should have followed them," says Sherrill.
Instead he went home because his wife needed him. If only, he says, he could turn back time.
"I had an opportunity to do something that if I would have done know what to do. It would have changed the circumstances. We wouldn't be here talking today," says Sherrill. "I don't pass 71st and Riverside without thinking about it."
Sherrill who understands he can’t change what happened but now in taking the stand he hopes he can play even a small role in bringing Baker and her family justice.
"It's going to take time to work through I am a tender hearted guy," says Sherrill. "The truth will prevail I believe."
Jurors also heard from Baker’s sister Courtney Baker who was Bullock’s girlfriend and is the mother of Bullock’s young son.
Courtney Baker testified that Bullock told her to lie and he was with Courtney the day Cori disappeared. When in fact, Courtney told police he wasn’t with her and the Bullock told her “it was an accident and he didn’t mean to kill her.”
Court records also show Bullock later told police Cori had drown accidentally in the Arkansas River.
Bullock’s trial continues Friday morning at 9am.
Jurors also heard from a boy who found some of Cori Baker’s remains at the paintball park.
The medical examiner was never able to determine her exact cause of death due to the poor condition of the remains.