Updated

The police in this sprawling Southern California city have faced calls of resignation for their chief. Officers and their families have received death threats, leading some to move out of their homes. And now, they could be investigated after a violent confrontation led to the death of a mentally ill homeless man.

Fullerton officials have called a special meeting Friday to discuss whether to launch an inquiry into 37-year-old Kelly Thomas's death. His father, a former sheriff's deputy, moved toward a lawsuit Thursday by filing a claim against the police.

The claim — a precursor to a lawsuit — alleges violation of civil rights, negligence and conspiracy against the city, its police department and the officers that Ron Thomas says caused the death of his son.

"They've already offered me $900,000," he said. "I just laughed at them. For what you did, the negligence that you showed? Ideally, I'm maybe looking for something more like $10 million, $15 million."

"So many people need help, and they need to learn a lesson here. I see this as a win-win," he added.

Ron Thomas has said his son was a schizophrenic who chose to live on the streets, despite support from his family and friends. Kelly Thomas, like many of the city's homeless population, frequented a transit hub where officers on July 5 were investigating a report of vehicle break-ins.

Police have said Kelly Thomas ran when they tried to search his bag and that they struggled to arrest him on suspicion of possessing stolen goods.

Footage from a bystander's cellphone showed parts of the bloody encounter between Thomas and six officers, including a snippet in which he can be heard screaming for his father. Surveillance from a bus showed agitated passengers describing how officers beat and repeatedly used a stun gun on him.

After sustaining severe head and neck injuries, Kelly Thomas was taken off life support July 10.

Ron Thomas said he plans to go forward with a lawsuit to ensure evidence, such as 911 tapes, are preserved. Although his claim Thursday did not specify an amount, he has pledged to donate any settlement he might win to charities serving the homeless.

The incident has already upended the police force, with Chief Michael Sellers going on medical leave Wednesday amid public outcry and the calls for his resignation. No criminal charges have been filed against the six officers, who are on paid administrative leave.

Sgt. Andrew Goodrich, a police spokesman, said that those officers have received death threats in voicemails left at their homes. He said they were told to take precautions, and many moved out of their houses.

Their names have not been released by the department but have appeared on the Internet. Goodrich declined to specify how many received the threats.