By Troy Anderson
SANTA ANA, California (Reuters) - An Iraq war veteran already charged in the "thrill" killings of four Orange County homeless men has been linked by DNA evidence to the murders of the mother and brother of a high school friend, prosecutors said on Friday.
Orange County District Attorney Tony Rackauckas said former U.S. Marine Itzcoatl Ocampo will be charged on Monday with murdering Raquel Estrada, 53, and her son Juan Herrera, 34, who were found stabbed to death in their home in October.
The additional charges mean that Ocampo, 23, will face six counts of first-degree murder with special circumstances allegations. He had already been eligible for the death penalty if convicted at trial.
"The case has now expanded from murdering random, vulnerable strangers to murdering people he knew," Rackauckas told a press conference. "It is chilling to know that these murders took place two months before the murders of four homeless men began."
Like the victims in that brutal killing spree, Estrada and Herrera were both stabbed repeatedly -- the mother more than 30 times and son at least 60.
Earlier in the day prosecutors dropped murder charges in that case against Estrada's other son, Eder Herrera, 24, a friend of Ocampo from high school.
Rackauckas said Herrera had not been conclusively eliminated as a suspect. He said there was "significant evidence" that led to originally filing the charges against him.
Rackauckas said a witness had also spotted a person he believed to be Herrera dragging something into the house, where there was no sign of forced entry, and that his behavior on the night of the crime was suspicious.
He also cited Herrera's friendship with Ocampo and said the two men lived about a mile apart.
The serial stabbing murders of four transients in December and January rattled Orange County residents before Ocampo was chased down by bystanders and arrested following the final stabbing on January 13.
Prosecutors say all four men were stabbed dozens of times and accuse Ocampo of targeting his final victim, John Berry, after the 64-year-old transient appeared in a Los Angeles Times article about the case.
Also slain were James McGillivray, 53, Lloyd "Jimmy" Middaugh, 42 and Paulus "Dutch" Smit, 57.
Ocampo served in the Marines from July 2006 to July 2010 and was deployed to Iraq in 2008, according to the Marines.
(Additional reporting by Dan Whitcomb and Mary Slosson; Writing by Dan Whitcomb)