A man who died last month after he was in Honolulu police custody was put into a chokehold by the person accusing him of stealing a vehicle, according to a Medical Examiner’s report.

Stephen Dinnan, 35, was running away from police June 3 when the man reporting an auto theft stopped him and put him in a chokehold, the report said. The auto theft complainant and the officer arrived at the Waimanalo home together. The man released the chokehold after the officer told him to, and Dinnan was still conscious.

Dinnan became unresponsive after he was handcuffed while prone, said the autopsy report by Dr. Kanthis De Alwis. He was taken off life support after he was pronounced brain dead the next day.

De Alwis ruled it a homicide with a cause of death listed as asphyxia due to compression during prone restraint.

Police said at the time that Dinnan fled when officers arrived at the Waimanalo home to locate a stolen vehicle, and he fought off attempts to detain him. Dinnan became unresponsive shortly after he was brought under control, police said.

Police are conducting an internal investigation. The officer involved, a 26-year veteran of the force, was placed on administrative leave. He was later returned to active patrol duty, but after the autopsy report was released, he was re-assigned to desk duties, a police spokeswoman said Wednesday.

“He brought the civilian there,” said Myles Breiner, an attorney representing Dinnan’s girlfriend, Shardeh Serhant, the mother of their two children. The family is claiming excessive force and police misconduct. “This officer, in my opinion, violated proper protocol.”

Police declined to comment.

Serhant’s previous attorney has said Dinnan wasn’t involved with any stolen vehicle and wasn’t running from police.

Breiner said he asked the FBI to investigate because he doesn’t believe Honolulu police will conduct an impartial investigation. The FBI won’t confirm whether there is such an investigation.

Breiner said he’s not yet exploring a lawsuit. “I just want a proper investigation by an independent agency,” he said.