A man is believed to have swallowed industrial cleanser he slowly collected while in custody and died while awaiting trial in the killings of four homeless men and two others. His lawyer, Michael Molfetta, said the incident raised serious questions about Orange County jail deputies' supervision of mentally ill Itzcoatl Ocampo. Ocampo, 25, a native of Mexico and a former US marine, was found shaking and vomiting in his cell last Wednesday and taken to a hospital where he was pronounced dead the next day. Molfetta said investigators believed Ocampo waited until he had accumulated enough Ajax industrial cleaner for a lethal dose, then ingested it. "If you spent three minutes with Ocampo, you were acutely aware he had mental issues. They were severe and they were obvious and they definitely were not contrived," Molfetta said. "This guy should have garnered the highest level of scrutiny." Prosecutors say Ocampo stabbed four homeless men in what they called a serial thrill-kill rampage in late 2011 and early 2012. He targeted his homeless victims because they were vulnerable and because he felt they were a blight on the community, authorities said. He was charged with four counts of murder, with special allegations of multiple murders, lying in wait and use of a deadly weapon. In one instance, prosecutors said Ocampo selected as his next victim a homeless man featured in a Los Angeles Times story about the killings. His parents separated in 2010 and his father became homeless after losing his job. During the killing rampage, Ocampo visited his father on the streets and warned him about the dangers of being homeless, even showing him a picture of one of the dead men.