SANTA ANA  (AP) — An Iraq war veteran indicted in the murders of six people in Orange County, including four homeless men, told a police detective after his arrest that he joined the Marine Corps because he needed to kill, according to court documents obtained by the Orange County Register .

Itzcoatl “Izzy" Ocampo said he was disappointed when he did not see any combat during a six-month tour of duty in Iraq when he "became a truck driver instead of a killer," according to a transcript of a secret hearing of the Orange County grand jury obtained by the newspaper.

"He felt in order to become a real Marine, he needed to kill," Detective Daron Wyatt told the grand jury. Wyatt took Ocampo's confession a few hours after he was arrested following the stabbing death Jan. 13 of the fourth homeless man outside a Carl's Jr. fast-food restaurant in Anaheim.

Ocampo told Wyatt that he had planned to continue killing people and hoped to build a kill list with 16 names before he was finished, according to the transcript.

"He said he needed to keep killing," Wyatt told the grand jury. "And he actually had predesigned that he was going to select 16 victims. ... He told me that Charles Whitman (the Texas Tower killer) had killed 16 people. ... And that Charles Whitman had been a Marine."

Ocampo was charged in an amended complaint in February with the murders of four homeless men in December and January, and with murdering Raquel Estrada, 53, and her son, Juan Herrera, 34, in their Yorba Linda home. Estrada's youngest son initially was charged with the attack.

Ocampo told Wyatt during one interrogation after he waived his right to remain silent that he killed the four homeless men because "he felt that he was somewhat doing a service to the community, because the homeless population had become a blight to the community."

Wyatt also testified that Ocampo said he chose his victims "because they were available and vulnerable."

The grand jury transcript also revealed that Wyatt described how Ocampo claimed he studied the human anatomy to find out the best way to kill. "He said he specifically targeted the throat to kill people, to sever the esophagus," Wyatt testified. "That he (also) targeted the head, because he had seen in the movie 'Terminator 2' that it was a quick kill."

Ocampo has pleaded not guilty to all charges. His trial is tentatively scheduled for Sept. 10