OAKLAND, Calif. -- Former BART police officer Johannes Mehserle did meet with investigators probing the New Year’s Day fatal shooting of a Hayward man but chose to invoke his Fifth Amendment rights against self incrimination, officials said Monday.

BART general manager Dorothy Dugger and transit police chief Gary Gee told an afternoon news conference that Mehserle was questioned within three hours of the fatal shooting of Oscar Grant III, but quickly asked for an attorney, refusing to cooperate.

The transit agency has been under fire for its handling of the case and among the most emotional complaints was that Mehserle had yet to be questioned. Monday’s announcement was the first public acknowledgement that Mehserle – who has resigned from the BART police force – has been questioned.

Mehserle's attorney, Christopher Miller, did not immediately return a call for comment.

Though officials completed their preliminary investigation of the New Year's Day fatal shooting, BART Police Chief Gary Gee said his department did not make a recommendation on whether charges should be filed against Mehserle.

Witnesses say Mehserle fired into the back of 22-year-old Oscar Grant while the man was lying facedown on a train platform at Oakland's Fruitvale station. Grant and others had been pulled off a train after reports of fighting, as New Year's Eve revelers were shuttling home after midnight.

The shooting was captured on several cell phone cameras and widely viewed on the Internet.

BART officials said their report includes interviews with seven officers and 14 witnesses at the scene. Mehserle, who has resigned from the force, filled out a basic incident report after the shooting but has refused to be interviewed by investigators, Gee said.

"We urge the district attorney to expeditiously review all the evidence available to him and bring this investigation to a conclusion," BART general manager Dorothy Dugger said in a news conference.

Alameda County District Attorney Tom Orloff has said he hoped to decide by next week whether to bring criminal charges.

Some have speculated that the officer may have intended to fire a stun gun but accidentally pulled his firearm instead.

Gee said Monday that Mehserle did have a stun gun at the time of the shooting -- located on the opposite side of his belt from the firearm -- and did not use it. The chief declined to discuss any other specifics of the report, including whether investigators found the shooting was intentional or accidental.

"It is our hope that this brings everyone one step closer to finding out all relevant details and ensuring this type of incident never repeats itself," Jesse Sekhon, president of the BART Police Officers Association, said in a statement after the news conference.

The shooting has inflamed long-running tensions between law enforcement authorities and many African-American residents in Oakland. Hundreds of protesters have taken to the streets calling for the prosecution of Mehserle, with one rally last Wednesday spiraling into violence and resulting in more than 100 arrests and dozens of businesses damaged.

Gregory Hunter, deputy director of Oakland's Office of Economic Development and Redevelopment, clarified Monday his previous statement that more than 300 businesses were affected by the violence, saying he now estimates no more than 45 were actually damaged.

"The whole world saw what happened. It's a shame and disgrace that this person has not been arrested," U.S. Rep. Barbara Lee, D-Oakland, said in an interview Monday in Washington.

Asked whether a federal civil rights investigation might be called for, Lee said she wanted to see how the local investigation proceeded but added: "I'm ready to take the next step whatever that might be."

Meanwhile, U.S. Justice Department has sent mediators to Oakland to help resolve the tensions, according to a memo notifying Lee and Sens. Dianne Feinstein and Barbara Boxer on Thursday.

The officials are from the department's Community Relations Service, which was created by the 1964 Civil Rights Act to help resolve and prevent racial and ethnic conflict and violence.

The memo, obtained by The Associated Press on Monday, says the mediators will meet with local law enforcement and black community leaders, conduct an assessment and provide any necessary follow-up.

The Oakland Police Department also has launched an independent probe of the shooting, and California Attorney General Jerry Brown said Saturday he would assign a state prosecutor to monitor the local investigation.