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Los Angeles Times, Allen J. Schaben) NO FORNS; NO SALES; MAGS OUT; ORANGE COUNTY REGISTER OUT; LOS ANGELES DAILY NEWS OUT; VENTURA COUNTY STAR OUT; INLAND VALLEY DAILY BULLETIN OUT; SAN BERNARDINO SUN OUT; MANDATORY CREDIT, TV OUT, Associated Press
In this Jan. 5, 2012 photo, John Berry, 64, who is homeless, listens to Anaheim Police Sgt. Mike Lynch warn him about the suspected serial killer in Orange County and how transients can protect themselves, in Anaheim, Calif.

YORBA LINDA, Calif. — The 23-year-old man suspected in the deaths of four homeless men in Southern California is a former Marine who became isolated after returning from Iraq and never got over the combat death of his best friend.

Family and friends said Sunday that Itzcoatl Ocampo was a fun-loving teen when he joined the military, but after he was discharged and returned home, he kept to himself and trusted no one.

They also say he never recovered after his best friend died in combat in Afghanistan.

Ocampo has been living with his uncle, mother, brother and sister in a small house three miles from where he was chased by citizens and arrested Friday night after the most recent killing of a homeless man.