Report: Dad of suspect in Calif. homeless killings also homeless January 16, 2012 -- Updated 1911 GMT (0311 HKT) Itzcoatl Ocampo, 23, is accused of killing four homeless men, police say. Report: "My son's always been a role model," the suspect's father says Refugio Campo tells a newspaper he lives in a parked semi-trailer cab His son is accused of killing four homeless men in Southern California Campo says his son changed after military service in Iraq (CNN) -- The father of the man police accuse of killing four homeless people in California is himself homeless, according to a published report. Refugio Ocampo, who lost his home in 2008 and now lives in the cab of a semi-trailer parked in Fullerton, California, said it was hard to believe his son could be involved in the killings. I saw him so many times giving the last money he had in his pocket ... to the homeless, to the people that (are) asking for some help. ... My son's always been a role model," Ocampo said in a video interview posted on the newspaper's website. Ocampo, 50, told the Orange County Register that his son, worried about his father's safety, had recently pointed out an FBI warning about homeless men being killed in the area. Authorities accuse his son, 23-year-old Itzcoatl Ocampo, of killing four homeless men. Police arrested him Friday night after he allegedly stabbed a transient to death in Orange County, Anaheim Police Sgt. Bob Dunn said Sunday. The suspect has not been arraigned, and police have not detailed evidence behind their accusation. Refugio Ocampo said his son was a Marine in Iraq, and returned a changed man. He started talking about things that "didn't make any sense," like the end of the world. "They killed the person he was," he told the Orange County Register. And that's the only possibility I can think of that he would do something like that. Authorities had been searching for a serial killer after three homeless men were stabbed to death over 10 days last month in Anaheim, Brea and Placentia. Police had released a surveillance camera image of the suspect taken December 20. It shows the suspect standing a few feet from the victim, who appears to be lying on the ground next to a strip mall, according to police. CNN's Gabriel Falcon contributed to this report.