HAYWARD --

The best friend of Oscar Grant who was there the night a BART police officer fatally shot the unarmed man was shot and killed at a Hayward gas station, authorities and friends said Saturday.

Johntue Caldwell, 25, of Fremont was found behind the wheel of a Cadillac parked at the Union 76 gas station at West Tennyson Road and Calaroga Avenue about 5:35 p.m. Friday, according to police and friends.

The victim had been sitting in the Cadillac when someone walked up to the vehicle and fired several rounds, said Hayward police Lt. Roger Keener. The assailant fled and was not located after a search of the area.

The motive for the slaying was not known, but police do not believe this was a random act, Keener said.

"Investigators will be focusing on learning anything they can about this incident from people who may have been in the area at the time," Keener said. "Through their investigation, they also expect to determine if the victim was the intended target of this attack."

In 2010, Caldwell filed a $5 million federal civil rights lawsuit, saying he was mistreated by a second BART police officer, Marysol Domenici, before Officer Johannes Mehserle shot Grant in the back on the platform of Oakland's Fruitvale Station early Jan. 1, 2009. Mehserle was recently released from custody after serving half of a two-year prison term for involuntary manslaughter.

Caldwell, the father of two young sons, was the godfather of Grant's daughter, Tatiana, now 7, who received a $1.5 million settlement from BART in connection with Grant's death.

Caldwell's suit, which is still pending, said Domenici ordered him to the ground, threatened him with a Taser, touched the stun gun to his face and cursed him using a racial slur. Caldwell was "mentally and emotionally injured," his attorneys wrote.

Dale Allen, an attorney for BART, said after the suit was filed that Caldwell had a "significant criminal history" and was one of three men who cursed at and physically challenged officers as they detained Grant and three others after a fight on a train.

But John Burris, an attorney for Grant's family whose civil suit against BART officers is pending, said Saturday, "Nothing I know about Johntue says that he was involved in any illegal activity."

Burris said, "Johntue was a wonderful young man. He had career objectives. He and his mother were very, very close. He and Oscar had been friends since early childhood. They were as close as brothers could be, and this is a tragedy of the highest order. It's hard to imagine that another young man of that relatively small group of people is dead."