The sister of a man fatally shot by a Tennessee police officer last year has filed a wrongful death lawsuit in federal court alleging excessive force.

Channara Tom Pheap, 33, was running away and “posed no imminent threat” to Knoxville Police Officer Dylan Williams when Williams shot him in the back last August in the parking lot of an apartment building, according to the lawsuit filed Wednesday by Pheap's sister Sophia Pheap.

Williams has disputed that account and said he shot Pheap after the man tried to choke him and then wrestled away his Taser and shocked him with it.

In November, Knox County District Attorney General Charme Allen ruled that Williams’ use of deadly force was appropriate and legal.

The lawsuit says the city and the police department have consistently failed to properly train and discipline officers who use force. It seeks $10 million in damages from the city, news outlets reported.

Police spokesman Scott Erland said Thursday that the city doesn't comment on pending litigation.

At the time of the shooting, police said Pheap, who is of Cambodian descent, was killed after a physical struggle.

The lawsuit says Williams, who is white, was looking for a female driver suspected of fleeing a traffic accident and stopped Pheap and began to search him. The lawsuit says Pheap tried to get away and the two struggled.

Williams fired his weapon when Pheap was more than 13 yards (12 metres) away and fleeing, according to the lawsuit.

“At the moment Officer Williams fired the two shots at Mr. Pheap and killed him, the altercation between the two men had ended,” the lawsuit states. “They were separated by approximately 40 feet, by one witness account, with Mr. Pheap unarmed and running away from Officer Williams."

Williams said he fired his weapon because Pheap had shot him with a stun gun, and he thought the hit-and-run suspect would incapacitate him.

Prosecutors last year determined that Williams feared for his life and said forensic evidence and witness accounts backed up Williams' version of events.

The lawsuit says the incident is an example of how officers are improperly trained in nonviolent de-escalation techniques and the proper use of nonlethal force.

Don Bosch, Williams’ attorney, told WBIR-TV on Wednesday that his client was not at fault.

“While Mr. Pheap’s death was tragic, Officer Williams was left with no other choice but to defend himself and others from Mr. Pheap’s unlawful actions. We are confident, as with past legal reviews, that any future legal scrutiny will demonstrate Officer Williams acted appropriately.”

News from © The Associated Press, 2020