According to Vargas, Grant was not resisting when the gunshot was fired. Vargas said she was standing only about 5 feet away from the shooting scene. She also said she resisted an officer's attempt to confiscate her camera.

Vargas, who said she was on her way home from a New Year's celebration along the Embarcadero in San Francisco when she witnessed the shooting, contended that Grant's "rights were definitely violated" by police.

BART officials have said Grant was unarmed and implied the shooting was an accident, saying the officer's gun discharged while he and four other officers responded to reports that two groups of young men were fighting on a train that had come from San Francisco and was en route to the Dublin/Pleasanton station.

Grant's family in Hayward has formally hired attorney John Burris to look into the circumstances surrounding his death.

The Oakland attorney, who has filed numerous lawsuits against police departments on behalf of family members of people who have been shot and killed by officers, scheduled a Sunday morning news conference to discuss developments in the case.

"It's an outrageous set of facts. My sense is clear that this was an unjustifiable shooting," Burris said based on witness statements, but prior to the videotape being made public. "There were no movements and he was not trying to overrun the police officer. A gun cannot discharge accidentally, you have to have your finger on the trigger."

"When conduct like this occurs, there is a price to pay," he added. "Police have to be held accountable when they engage in this kind of unlawful conduct."

BART officials have not released the name of the officer who shot Grant. They said the officer has worked for BART for nearly two years and was placed on administrative leave following the shooting.

The Alameda County District Attorney's office is handling the official investigation into the shooting. The D.A.'s office has not commented on the case.