SANTA ANA, Calif. – An Iraq War veteran is accused of carefully stalking his victims from among the homeless living in Southern California. He would then stab them repeatedly with a knife that could cut through bone, authorities say.

For his fourth victim, they say, Itzcoatl Ocampo selected a homeless man featured in a Los Angeles Times story about a killing spree that terrorized those living on the streets for weeks.

And Ocampo had plans for more, until he was chased down by bystanders Friday night after the fatal stabbing of a 64-year-old homeless man.

“He was a monster,” Orange County District Attorney Tony Rackauckas told reporters at a news conference. “He was a terrible threat, particularly to the homeless people in our community.”

Ocampo was charged Tuesday with four counts of murder. Three victims were stabbed more than 40 times each with a single-edged blade at least 7 inches long.

Authorities declined to say whether they had identified a motive. Rackauckas said he had no indication that Ocampo was mentally ill.

Ocampo’s family said the 23-year-old was a troubled man after he returned from Iraq in 2008.

The killing spree began in December, prompting police and advocates to urge the homeless to sleep in groups or in shelters.

Like the men Ocampo is accused of preying on, his father is homeless.

Days before his arrest, Ocampo warned his father of the danger of being homeless. He showed him a picture of one of the slain men.

“He was very worried about me,” his father said. “I told him, ‘Don’t worry. I’m a survivor. Nothing will happen to me.’ ”