LOS ANGELES: A former Los Angeles police officer who has threatened to kill police was being sought in two weekend killings and was a suspect in an overnight shooting that killed one officer and critically wounded another, authorities said, calling him "armed and dangerous."

Christopher Jordan Dorner 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.

Dorner, 33, implicated himself in the killings with a multi-page "manifesto" that included threats against several people, including members of the Los Angeles Police Department, police said. They gave no further details on the document.

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.

Authorities were seeking the public's help in finding Dorner.

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

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.