ANTIOCH — New details have surfaced on authorities’ decision not to file criminal charges in the February shooting death of a San Ramon man, but the victim’s family continues to dispute that it was an act of self-defense.

Demarco Childs, 31, was shot at least four times at a Chevron gas station on Feb. 13. He died in a hospital two days later. A coroner’s report released in June says Childs was shot with his own handgun, after getting into an argument with a man with whom he had a history and displaying the gun at his waistband, leading to a struggle where the other man grabbed the weapon.

Police say the shooter — whom this newspaper is not naming because he wasn’t charged with a crime — was fighting for his own life, and only fired shots after Childs declared he had a second gun strapped to his ankle, then reached for his pant leg. No guns were found on Childs’ body, authorities said.

But Childs’ family is not accepting the police department’s assessment and is lobbying the District Attorney’s Office to re-examine the case. Derrick Childs, Demarco Childs’ older brother and a legal analyst for prominent civil rights attorney John Burris’ law firm, has spent much of the past six months compiling evidence in the case, which he said he is planning to turn over to the DA’s office next week.

“I’m just trying to get some justice for my brother,” Derrick Childs said, describing his brother as a “loving, laid-back guy.” He later added, “I’ve been working on it, and based off jury instructions, this case is not a self-defense case. … We may need to have Attorney General Kamala Harris’ office look into it if the Contra Costa DA’s office doesn’t want to do anything about it.”

But Deputy District Attorney Paul Graves, who made the decision not to file charges, said it was a clear-cut decision and that he didn’t think prosecutors would be able to prove the shooter’s actions “were not in self-defense, or in defense of others.”

Antioch police Sgt. Tom Fuhrmann said investigators reviewed security footage from the gas station that depicted the entire incident and weighed that against a lengthy statement by the shooter, who cooperated with authorities. He said Demarco Childs and the shooter had conflicts in the past, and the video footage shows Childs showing the other man that he had a gun, then the two struggling over the weapon.

The other man gained control of the weapon, and later told police that he shot Childs only after Childs claimed to be reaching for a second gun at the base of his pant leg.

“Every shot has to be justified, so once (Demarco) is basically at a state where he’s no longer a threat, if (the shooter) were to have given him a shot at that point, then I think it would have been a different story entirely,” Fuhrmann said. “In the video (after shots were fired), (the shooter) holds (Childs) at gunpoint until officers come, then he puts his hands up, puts the gun on the ground, and follows officers’ orders promptly.”

Derrick Childs said that among the evidence he’s gathered is “independent video” that shows the shooter standing over Childs and firing unprovoked shots at him. Authorities say they’ve yet to view that evidence. The coroner’s report states that there were three gunshot wounds, as well as two graze wounds, found on Childs’ body.

Two of those wounds were to his backside, one severing an artery, one hit him in his knee, and the graze wounds are to his chest and arm.

The coroner’s report also states that the shooter had a restraining order against Demarco Childs, but Contra Costa civil records indicate one was never filed.

Contact Nate Gartrell at 925-779-7174 or follow him at Twitter.com/NateGartrell.