The video shows Mr. Arbery trying to grab the shotgun from Travis McMichael’s hands, Mr. Barnhill wrote. And that, he argued, amounts to self-defense under Georgia law. Travis McMichael, Mr. Barnhill concluded, “was allowed to use deadly force to protect himself.”

He noted that it was possible that Mr. Arbery had caused the gun to go off by pulling on it, and pointed to Mr. Arbery’s “mental health records” and prior convictions, which, he said, “help explain his apparent aggressive nature and his possible thought pattern to attack an armed man.”

After Mr. Barnhill recused himself, the case was assigned to Tom Durden, in the city of Hinesville, Ga., who must now decide whether to present the case to a grand jury for possible indictments. In an interview last week, Mr. Durden said his team had begun reviewing the evidence. “We don’t know anything about the case,” he said. “We don’t have any preconceived idea about it.”

The police report is based almost solely upon the responding officer’s interview with Gregory McMichael, who had worked at the police department from 1982 to 1989. The responding officer describes him as a witness. According to the report, Mr. McMichael told the officer that he and his son pulled up near Mr. Arbery, that his son got out of the truck with the shotgun, and that his son and Mr. Arbery then fought over the weapon, “at which point Travis fired a shot and then a second later there was a second shot.”

Michael J. Moore, an Atlanta lawyer who formerly served as a U.S. attorney in Georgia, reviewed Mr. Barnhill’s letter to the Glynn County Police Department, as well as the initial police report, at the request of The Times. In an email, Mr. Moore called Mr. Barnhill’s opinion “flawed.”

In his view, Mr. Moore said, the McMichaels appeared to be the aggressors in the confrontation, and such aggressors were not justified in using force under Georgia’s self-defense laws. “The law does not allow a group of people to form an armed posse and chase down an unarmed person who they believe might have possibly been the perpetrator of a past crime,” Mr. Moore wrote.

Nearly two months after the shooting, residents of Satilla Shores remained on guard. One woman angrily asked what a reporter was up to, and another approached almost immediately with similar questions, announcing that she was armed and that she had notified the police.

Mr. Vaughn, the football coach, said on Sunday that he and other activists had come up with a plan to keep the pressure on the authorities. They plan to drive to Mr. Durden’s office in Hinesville, he said, about an hour away. They will mark off spots on the sidewalk so that they remain several feet apart. And they will enter the building, one by one, to ask why the men who chased Mr. Arbery have not been arrested.