OAKLAND -- Alameda County prosecutors plan to charge a second man this week with murder in the shooting death of Oakland Tribune freelance photographer Lionel Fluker, a defense attorney confirmed.

Donel Poston, 37, will be charged with murder in an unusual, last-minute decision that was made as attorneys in an attempted-murder trial against Poston were set to begin picking jurors.

Poston faced an attempted-murder charge in connection to the gunfight that led to Fluker's death April 5 when the photographer was randomly hit in the head by a stray bullet as he drove through the intersection of Seminary Avenue and MacArthur Boulevard.

Anthony Lister, 38, a 10-time felon, has already been charged with murder in the death of Fluker because investigators determined, through ballistics, that the bullet that killed Fluker, 54, came from Lister's 9-mm handgun.

Poston, who fired a .40-caliber handgun, was never charged in connection to Fluker's killing; he was only charged with attempted murder for shooting at Lister after the two got into a fist fight at a gas station near the corner of Seminary Avenue and MacArthur Boulevard.

David Bryden, Poston's defense attorney, planned to argue at trial that his client was acting in self-defense when he shot Lister. It was an argument that appeared to have considerable merit as a surveillance video shows Lister initiating the fight with Poston and then reaching for a gun, Bryden said.

Also, in charging Lister with murder, the district attorney's office has said that it believes Lister was trying to kill Poston when he shot Fluker. That argument bolsters Poston's self-defense claim.

At the same time, prosecutors would have to argue at Poston's attempted-murder trial that he was trying to kill Lister, which would then give Lister a valid self-defense claim at his murder trial.

Rather than face a loss at trial and find itself in the position of arguing against itself, it appears District Attorney Nancy O'Malley's office decided to drop the attempted-murder case against Poston and recharge the Oakland resident with the murder of Fluker.

That charge, Bryden said, would then make Poston a co-defendant for murder with Lister. Both would be tried together and an argument to a jury could be that both were engaged in unlawful activity by shooting firearms and both should be held responsible for Fluker's death.

Bryden said he was disappointed that his client must now defend against a murder charge when all he was trying to do was save his own life against a man who was chasing him with a gun.

"I still believe that Poston is a victim, too," Bryden said. "He was running away."

It remains unclear why prosecutors did not decide to charge Poston with murder from the start.

Deputy district attorney Scott Ford declined to comment.

The murder charge against Poston is expected to be filed Thursday, when Alameda County Superior Court Judge Jeffrey Horner scheduled the case to continue.