US police launch huge manhunt for alleged cop killer

California police launched a massive manhunt Thursday for a former cop accused of killing three people, including another officer, and posting chilling threats to kill more.

In an Internet manifesto threatening police and their families, Christopher Dorner warned about "terminating" a retired policeman he blamed for his sacking five years ago and called lesbians and Asians "high value" targets.

The LA Police Department, backed by agencies including the FBI, said it was protecting over 40 possible targets, some of them identified in the "rambling" online manifesto by Dorner, a 33-year-old US Navy reservist.

"Dorner is considered to be armed and extremely dangerous," LAPD chief Charlie Beck told a press conference, adding that the suspect has "multiple weapons at his disposal, including assault rifles."

"The criminal with whom we are dealing has made it clear that he considers police officers and their families fair game," added Sergio Diaz, police chief in Riverside, east of Los Angeles, where one officer was killed.

In a flurry of police action including false alerts, a naval base near San Diego was put on lockdown after a possible sighting and an attempt to steal a boat nearby, prompting speculation Dorner planned to flee by sea to Mexico.

Dorner's wallet and an ID badge were found overnight in San Diego, two hours south of Los Angeles, police said, while there also reports of police searches in neighboring Nevada, where he has a house near Las Vegas.

Dorner was already wanted over the suspected revenge killing on Sunday of a couple, Keith Lawrence and Monica Quan, who was the daughter of Randy Quan, a retired police officer he blamed for his firing.

Then he allegedly attacked two other officers overnight in Riverside, killing one and injuring the other. Another officer was injured in a separate incident in nearby Corona.

In addition, two civilians were injured early Thursday when police officers opened fire on them in a vehicle they believed to be Dorner's. "Tragically we believe that this was a case of mistaken identity," said Beck.

Dorner posted his manifesto online Monday, saying he was not afraid to die because he had already died when he was dismissed in September 2008 for making false statements about his training officer.

"I never had the opportunity to have a family of my own, (so) I am terminating yours," he wrote to Randy Quan.

"Suppressing the truth will (lead) to deadly consequences for you and your family. There will be an element of surprise where you work, live, eat and sleep," he said, referring to Quan and several others.

Dorner is described as black, six feet (1m80) tall and 270 pounds (120 kilos) in weight. He was said to be driving a gray Nissan Titan pickup, and may have changed the license plates.

In his 20-page manifesto, published by ABC news and other media, Dorner said he was determined to clear his name.

"The attacks will stop when the department states the truth about my innocence, PUBLICLY!!! I will not accept any type of currency/goods in exchange for the attacks to stop... I want my name back, period."

He also singled out lesbians and Asians as targets. "Those lesbian officers in supervising positions who go to work, day in day out, with the sole intent of attempting to ... degrade male officers. You are a high value target.

Riverside police chief Diaz said his opinion of Dorner was "unprintable," adding: "The manifesto I think speaks for itself, in terms of evidence of a depraved mind and heart."

LAPD chief Beck said Dorner's police and military training made the threat all the more serious. "He knows what he's doing. We trained him ... he's also a member of the armed forces," he said.

"It is extremely worrisome and scary." Asked what message he wanted to give Dorner, he said: "I would tell him to turn himself in. This has gone far enough.

"Nobody else needs to die."