Feb. 7, 2013 -- The rage-filled "manifesto" written by former police officer Christopher Dorner before he went on an alleged cop killing spree around the Los Angeles area was dismissed by the head of the Los Angeles Police Department today as "self-serving" and "ramblings on the Internet."

Dorner is believed to have killed one police officer and injured two others early this morning, in addition to killing two civilians, on a spree that he threatened would have a "high action of violence" in an angry missive posted to his Facebook wall earlier this week.

Police throughout the Los Angeles and Southern California region were working to apprehend Dorner.

In the letter, Dorner detailed his grievances with his former employer, the Los Angeles Police Department, including his struggles with the department's internal affairs department, which ultimately ended in his getting fired, according to the manifesto. He blamed the problems with the LAPD for inspiring his killing spree.

Dorner accused the department of being racist and using excessive force.

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"The department has not changed since the Rampart and Rodney King days. It has gotten worse," Dorner wrote. "I know I will be vilified by the LAPD and the media. Unfortunately, this is a necessary evil that I do not enjoy but must partake and complete for substantial change to occur within the LAPD and reclaim my name."

Dorner named members of the LAPD whom he would target and said they would not be safe at home or at work.

"I will bring unconventional and asymmetrical warfare to those in LAPD uniform whether on or off duty," he wrote. "You will now live the life of the prey."

Today, Los Angeles Police Chief Charlie Beck curtly dismissed the letter.

"This is a homicide suspect who has committed atrocious crimes. If you want to give any attribution to his ramblings on the Internet, go ahead, but I do not," he said.

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Much of the letter focused on an episode in which Dorner said he saw a fellow officer use excessive force to kick a suspect who was schizophrenic. He reported the incident to the department's internal affairs department, kicking off a lengthy investigation that ultimately led to his dismissal from the department for making false statements.

"I had broken their supposed 'Blue Line,'" he wrote, referring to the notion that police officers protect one another. "It is clear as day that the department retaliated toward me for reporting [the officer]. ... The department stated that I had lied and made up the report."

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Dorner said the incident cost him greatly at the department and in his personal life, fueling his killing spree.

"The LAPD's actions have cost me my law enforcement career," he said. "They cost my naval career. ... I've lost my relationship with my mother and sister because of the LAPD. I've lost a relationship with close friends because of the LAPD. In essence, I've lost everything because the LAPD took my name and new (sic) I was INNOCENT!!!" he wrote.

"This is my last resort. The LAPD has suppressed the truth and it has now lead to deadly consequences," the letter said.

Beck, the current LAPD chief, said that the internal affairs case that Dorner spent much of the letter focusing on had been treated fairly through the police department's review board.

"That case was thoroughly adjudicated. It went through several levels of review up to the point where even a civilian representative listened to the entirety of the case. You will find Dorner's statements to be self-serving and the statements of somebody who was extremely unhappy in his lot in life," Beck said.

The police chief of nearby Riverside, Calif., also dismissed the writings after Dorner allegedly shot and killed a Riverside police officer in the early hours of Thursday morning. Dorner pulled up across from two Riverside officers stopped at a traffic light in their patrol car and used his rifle to shoot them, killing one and injuring the other, according to Chief Sergio Diaz of the Riverside Police Department.

"The manifesto speaks for itself in terms of a depraved and cowardly mind and heart, and the way he ambushed your public servants speaks for itself," Diaz said.

Dorner's letter ended with a violent warning to cops, however, and one that kept police heavily armed and on edge today despite their dismissal of the letter's content. He said he would use all of his tactical knowledge from his police and naval experiences to avoid being caught.

"You are aware that I have always been the top shot, highest score, an expert in rifle qualifications in every unit I've been in," he wrote. "I will utilize every bit of small arms training, demolition ordnance, and survival training I've been given."