An Iraq war veteran accused of knifing four homeless men to death, stabbing them each dozens of times in a bloody killing spree that rattled Orange County, California, was charged on Tuesday with murder.

Former U.S. Marine Itzcoatl Ocampo was charged with four counts of first degree murder with special circumstances, making him eligible for the death penalty if he is convicted, Orange County District Attorney Tony Rackauckas said.

This 23-year-old man was a vicious killer, Rackauckas said at a press conference in Santa Ana. He had it in his mind to kill people and followed through with that. He is a monster.

Ocampo was chased down by bystanders and arrested on Friday night following the stabbing death of John Berry, a 64-year-old homeless man who Rackauckas said was targeted after appearing in a Los Angeles Times news story about the sensational case.

We believe that the evidence is going to show that the defendant specifically sought out the victim for participating in this article, Rackauckas said. He relished media attention of the crime and he stalked the victim until he got his prey.

Rackauckas said Ocampo is accused of first killing 53-year-old James McGillivray on December 20, attacking him as he slept behind a shopping center in the Orange County suburb of Placentia and stabbing him more than 40 times.

Video footage of the crime captured by a recently installed security camera shows the killer, dressed in dark pants and a black hooded sweatshirt, kneeling on McGillivray's chest as he stabs him in the head, neck and upper torso.

Eight days later the body of a second transient, Lloyd Jimmy Middaugh, 42, was found under a freeway underpass in Anaheim, stabbed more than 50 times in the head and torso.

Ocampo is also charged in the murder of 57-year-old Paulus Dutch Smit, who was stabbed more than 60 times behind the Yorba Linda Public Library. His body was found on December 30.

Rackauckas said all four of the victims were attacked with a 7-inch military-style knife and that in each of these cases the violence, the number of stabs wounds to each victim increased.

A knife matching that description was recovered near the spot where Ocampo was arrested, along with bloody clothing and gloves, Rackauckas said.

Ocampo's attorney, Randall Longwith, told Reuters he saw his client for the first time on Tuesday in the psychiatric ward of the Orange County Jail, where he was undergoing a mental evaluation.

I saw him for 15 seconds. He was naked but for underwear, and he was wrapped with a blanket and curled up in the corner of the cell, Longwith said.

I got on my hands and knees and talked to him through the food slot, he said. I introduced myself and told him what he should and should not do, and what his rights were and that his parents loved him.

Rackauckas said his office had not yet determined whether to seek the death penalty in the case, the first serial killings in more than two decades to hit largely suburban Orange County, southeast of Los Angeles.

Ocampo served in the Marines from July 2006 to July 2010 and was deployed to Iraq in 2008, a Marine spokeswoman said.