Dorner filed a lawsuit in an effort to try to keep his job, but that lawsuit was rejected, and so was his appeal. That chain of events appears to have triggered Dorner's alleged revenge rampage.
Dorner served as an officer with the LAPD from 2005 until 2008, when he was fired for making false statements.
It was August 2007 when the rookie police officer and his training officer responded to a call of a disruptive man at a hotel in the South Bay. Dorner had just returned home from his year-long deployment.
According to court papers, Dorner and his partner struggled with the man, identified as Christopher Gettler. The training officer Tased the suspect, who fell into some bushes before being handcuffed and taken into custody. But that's where Dorner's story differs. According to Dorner's so-called manifesto, his training officer "kicked the suspect twice in chest and once in the face. The kick to the face left a visible injury on the left cheek below the eye."
Several weeks later, Dorner reported his version of the story to his superiors. A panel investigated his claims, but the LAPD says Dorner fabricated the story because his training officer had written an unfavorable review of his performance.
"I think that in the analysis you'll find Dorner's statements to be self-serving, and the statements of somebody that is extremely unhappy with his life," LAPD Police Chief Charlie Beck said at a news conference Thursday morning.
Beck said the department conducted a thorough investigation of the incident and found that Dorner was lying.
"That case was thoroughly adjudicated, it was reviewed at multiple levels, it went to the ultimate form of review in the LAPD, a board of rights, where a two-command officer and a civilian representative hear the entirety of the case, as represented by an attorney, and make a judgment," Beck said.
In 2008, Dorner was fired from his job with the LAPD. He claims his dismissal was in retaliation for his report against his training officer.
In his Manifesto, Dorner stated: "Even [Getttler's] father stated that his son said he was kicked by [the training officer]..."
Gettler's father, Richard, said he believed that Dorner was telling the truth about the incident with his son, and he had a message for the accused murderer.
"He's obviously a man who wanted to be a good cop, and I'm sure once he testified against his mentor, I'm sure they gave him heck, he went through a living nightmare the last few years that he was an officer," Richard Gettler said.Christopher Dorner manhunt: See a timeline of key events
In 2009, Dorner filed suit in LA County Superior Court in an effort to keep his job. But that petition was rejected in May 2010. Dorner appealed that decision, but his appeal was rejected in October 2011.
In his manifesto, Dorner identified his training officer as one of his targets, saying: "You destroyed my life and name because of your actions. Time is up. The time is now to confess to Chief Beck."
But Beck says he's not interested in Dorner's opinions.
"You're talking about a homicide suspect who has committed atrocious crimes, and if you want to give any attribution to his ramblings on the Internet, go right ahead, but I do not," Beck said.
Police say Dorner started acting out on his revenge plot on Sunday night when he allegedly shot and killed 27-year-old Keith Lawrence and 28-year-old Monica Quan at their apartment complex in Irvine.
Police say he killed the couple because Quan's father is a former LAPD captain-turned-lawyer who was involved in the review process that led to Dorner's dismissal from the LAPD.
Dorner also had a long career in the Navy that started in 2002 and ended last Friday. The Navy reservist had reached the rank of lieutenant. His one overseas deployment sent him to Bahrain from 2006 to 2007.
He received several medals and ribbons, including the pistol expert medal and the rifle marksman ribbon. The military says these honors are common.