Christopher Dorner: Cop 'Disturbed' Claims Ex

Details are emerging about the former police officer at the centre of a massive manhunt as the high-altitude search for him enters its second day.

Court documents show an ex-girlfriend of Christopher Dorner, the suspect in three murders, called him "severely emotionally and mentally disturbed" after the two split in 2006.

In an online manifesto Dorner, 33, has vowed "warfare" against a list of "high value targets" whom he believes have wronged him.

Police say Dorner is out for revenge against people he sees as involved in his 2008 firing from the Los Angeles Police Department.

Officers have been sent to protect more than 40 potential targets, including police personnel and their families.

A former Navy reservist who served in Iraq, Dorner also goes into detail about how he was fired from the LAPD for whistle-blowing about what he claims was brutal behaviour by other officers.

He claims the department has not changed since the Rodney King beating incident and that he was out to correct the officers' "moral compass".

On Friday Irvine police officers and US Marshals served a search warrant on the Las Palmas home of Dorner's mother.

His mother and sister were home at the time and were cooperating, said Irvine Lieutenant Bill Whalen.

Dorner once lived at the home but did not appear to have been there recently, he said.

Police found Dorner's burned-out pickup truck abandoned on a mountain forest road on Thursday, and followed tracks they believed to be his leading away from the scene before losing the trail.

The hunt for Dorner continued on Friday in the Southern California ski resort community of Big Bear, even as a winter storm brought fresh snow to the mountain region 80 miles (130km) east of Los Angeles.

The FBI had joined the growing group of local law enforcement agencies searching for the suspect.

There have been no leads since then.

"Here's the bottom line: We don't know if he's on foot or not," said LAPD Deputy Chief Kirk Albanese. "Is he on foot up on the mountain? Is he down the mountain? We don't know."

The search for Dorner now stretches across California and Nevada and into Mexico.

Court documents obtained on Friday show Dorner unsuccessfully requested a restraining order against his ex-girlfriend after she posted his badge number on a website called Dontdatehimgirl.com.

In the online posting, Ariana Williams called Dorner "twisted" and "super paranoid" and warns other women on the website not to date him.

Williams' attorney could not be reached for comment.

Dorner is wanted for the killings of Monica Quan, the daughter of a former LAPD captain and her fiance, Keith Lawrence. They were found shot in their car at their condominium in Irvine on Sunday night, authorities said.

Ms Quan, 28, was an assistant women's basketball coach at Cal State Fullerton. Mr Lawrence, 27, was a public safety officer at the University of Southern California.

Ms Quan's father, who became a lawyer in retirement, represented Dorner in front of the Board of Rights, a tribunal that ruled against him at the time of his dismissal in 2008.

Authorities also said Dorner opened fire early on Thursday on police in cities east of Los Angeles, killing an officer and wounding another.

In his Facebook manifesto, Dorner says: "I am here to correct and calibrate your morale (sic) compasses to true north."

He said: "I will bring unconventional and asymmetrical warfare to those in LAPD uniform whether on or off duty. ISR is my strength and your weakness.

"You will now live the life of the prey. Your RD's and homes away from work will be my AO and battle space.

"I will utilize every tool within INT collections that I learned from NMITC in Dam Neck. You have misjudged a sleeping giant.

"There is no conventional threat assessment for me."

He also singles out various celebrities for praise, including Michelle Obama, Hillary Clinton, Charlie Sheen and Kate Winslet, but does not issue threats against them.

Dorner has a number of weapons including an assault rifle, according to LAPD Chief Charlie Beck.

Mr Beck said: "Of course he knows what he's doing; we trained him. He was also a member of the Armed Forces," he said. "It is extremely worrisome and scary."