Angry protesters gathered Saturday outside the police department of this Southern California city to decry the death of a homeless schizophrenic man who died after being beaten during a violent arrest, according to AP. About 400 people lined sidewalks outside the police station and chanted slogans such as "Justice for Kelly, No killer cops," and "No justice, no peace, no killer police." Many demanded the resignation of Police Chief Michael Sellers. "The police chief needs to resign and apologize to the victim's family," said Robert Giannasi, a San Diego resident who had driven up the coast to attend the protest over Kelly Thomas' death. "These people work for us, I don't see why they are trying to subvert the system." Like several other demonstrators, Giannasi said he had a family member with mental illness, so the manner of Thomas' death deeply resonated with him. "This could have been my brother or uncle," he said. Thomas had symptoms of schizophrenia and a 16-year string of arrests for everything from assault with a deadly weapon to public urination to jaywalking. Six officers who were trying to search his backpack July 5 after reports of break-ins at a Fullerton transit hub got into a violent fight with the 37-year-old. He later died of severe head and neck injuries. The lack of engagement and perceived secrecy in the case has frustrated many. Several demonstrators demanded the police release city surveillance camera footage they believe depict the beating. "Make it public," said Dana Pape, Thomas' stepmother. "It's torture for us. ... We need to see it." The protest was at least the third time demonstrators had gathered outside the police department since Thomas' death. Some carried signs bearing statements such as: "Protect and serve, not beat and murder." The drivers of many cars briefly stopped and drivers blasted their horns. Freddy Worth, a Long Beach resident, said he had a mentally ill brother who had spent some time on the streets. Tears welled in his eyes as he described why he came to Fullerton. "To let people know that the police are here to help the community, not harass the community," he said. "The (officers) need to be prosecuted and they need to be jailed." Not surprisingly, police stayed away. Lt. Scott Rudisil, who came to the door at the white, Spanish-ranch-style building, said no one from the department would be commenting. The victim's mother, Cathy Thomas, said her son chose to live on the streets and could have gone home if he'd wanted to. "The schizophrenia took over his mind," she said. A bystander recorded the incident with a cell phone. A bus surveillance tape showed agitated witnesses describing how officers beat Thomas and used a stun gun on him repeatedly as he cried out for his father. The police department has called the case an isolated incident and put the six officers on administrative leave. The FBI and the district attorney's office are investigating.