LOS ANGELES — A former Los Angeles police officer who has threatened "warfare" on former colleagues was the target of a manhunt Thursday after two weekend killings and an overnight shooting that killed one officer and critically wounded another.

Authorities called Christopher Jordan Dorner "armed and dangerous" and said a threatening manifesto had been found. Dorner was fired from the police department in 2008, and one of the weekend victims was the daughter of a former police captain who had represented him during his disciplinary proceedings.

San Diego police Sgt. Ray Battrick said Dorner's police badge and ID were found by a citizen near the city's airport and turned in to police.

The department has taken such protective measures as reassigning motorcycle officers to cars, Police Cmdr. Andrew Smith said.

Officials say Dorner shot at two Los Angeles Police Department officers, grazing one, then ambushed two police officers at a separate location, killing one and critically wounding the other. They had not been actively looking for him at the time.

Dorner also is wanted in the killings of Monica Quan and her fiancé, Keith Lawrence, who were found shot to death in their car Sunday night, Irvine police Chief David L. Maggard said Wednesday night. Quan, 28, was an assistant women's basketball coach at a local university. Lawrence, 27, was a public safety officer at the University of Southern California.

Dorner, 33, implicated himself in those killings with a multi-page "manifesto" that included threats against several people, including members of the Los Angeles Police Department, police said.

"We have strong cause to believe Dorner is armed and dangerous," Maggard said, adding that police and FBI were assisting in the case.

In San Diego, not far from the Mexican border, Detective Garry Hassen said a man matching Dorner's description tried to steal a boat from a city marina Wednesday night. When the engine failed to start, the suspect tied up an 81-year-old man who was on the boat and fled.

Dorner was with the police department from 2005 until 2008, when he was fired.

According to documents from a court of appeals hearing in October 2011, Dorner was fired after he made a complaint against his field training officer, Sgt. Teresa Evans. Dorner said that in the course of an arrest, Evans kicked suspect Christopher Gettler, a schizophrenic with severe dementia.

Following an investigation, Dorner was fired for making false statements.

Richard Gettler, the schizophrenic man's father, gave testimony that supported Dorner's claim. After his son was returned on July 28, 2007, Richard Gettler asked "if he had been in a fight because his face was puffy" and his son responded that he was kicked twice in the chest by a police officer.

Quan's father, a former police captain who became a lawyer in retirement, represented Dorner in front of the Board of Rights, a tribunal that ruled against Dorner at the time of his dismissal, police Capt. William Hayes told The Associated Press on Wednesday night.

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