What authorities are calling Chris Dorner's campaign of guerrilla warfare against his former comrades in the Los Angeles Police Department has its roots in a hotel lobby in San Pedro, the city's port district.
In July 2007, the former Navy officer was an LAPD probationary officer, riding patrol with a veteran of the force, when they were dispatched to check out a report of a disturbance at the DoubleTree Hotel. A man had refused to leave the premises and was sitting on the bench outside the lobby when they arrived.
Christopher Gettler had "a glazed look in his eyes," court documents later recounted, and he refused to get up and speak with police. Dorner and his training officer, Teresa Evans, started to take him into custody, but he refused to comply and took a swing at them.
Gettler's family later told investigators he had a history of mental illness. Dorner wrestled with him, and the two tumbled into a planter in front of the DoubleTree. Evans readied a Taser and warned the man to stop. He submitted only after she shocked him with the electronic device.
That's where the stories start to differ. And those differences led to an investigation by the LAPD's internal affairs unit, Dorner's eventual dismissal from the force and a long court battle to clear his name – a battle he was losing in California courts.
The LAPD starting hunting Dorner after concluding that he killed one police officer, wounded two others, and killed the daughter of his police union representative and her fiance on Sunday.
Two weeks after that encounter in San Pedro, Dorner went to a sergeant to report that Evans had kicked Gettler after he had given up. The LAPD investigated his complaint and ruled it "unfounded," based on accounts by three hotel employees, in May 2008.
Then the investigators' report turns to Dorner.
"The delay in reporting the alleged misconduct coupled with the witness' statements irreparably destroy Dorner's credibility, and bring into question his suitability for continued employment as a police officer," it states. The report found Dorner had made false statements to a superior while reporting the allegation that Evans had kicked the suspect and to internal affairs investigators looking into the claim.
It recommended his dismissal, a process that was completed by September 2008. In a letter to the department, provided to CNN by an LAPD source, Dorner threatened to retaliate against officers involved in his case and their families.
"The attacks will stop when the department states the truth about my innocence," he wrote. Referring to the LAPD's history of scandal, he wrote that the department "has not changed since the Rampart and Rodney King days. It has gotten worse."
"I know I will be vilified by the LAPD and the media," he wrote. "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."
But LAPD Chief Charlie Beck told reporters Thursday afternoon that no apology and exoneration would be forthcoming: "It is not going to happen."
Dorner grew up in southern California, listing several Los Angeles-area towns in his letter, before attending college at Southern Utah University. He was a running back on the school's football team before graduating with a degree in political science in 2001, Southern Utah athletic department spokesman Neil Gardner said.
"Chris Dorner is the last person I would ever think would do such," Gardner said Thursday. "He was a great kid."
College classmate James Usera said Dorner called him "out of the blue" four years ago, after not having spoken for several years after graduation. He complained about problems with the LAPD during the call, but Usera didn't recall the details.
"He did seem to be bothered by it or upset by it a bit, but certainly nothing that he said to me struck me as being a concern other than for concern for his employment," Usera told CNN.
"Never anything I experienced in a million years would lead me to conclude that this horrendous activity was imminent," he added.
Dorner joined the Navy after college, receiving a commission as an ensign in July 2002. He trained in river-warfare units and and served a 2006-2007 stint in Iraq guarding oil platforms, according to Pentagon records. He held a commission as a lieutenant until February 1 and was rated as a rifle marksman and pistol expert, according to the records.
He enrolled in the LAPD Academy in February 2005 and spent four months on the streets as a trainee before being recalled to active duty for his stint in Iraq, police records state.
Dorner went to court to challenge his firing, but both a trial court and a state appeals court upheld the LAPD's decision. In his letter to the LAPD, he says its actions had cost him not only his police job but his career in the Navy.
"This is my last resort," he wrote. "The LAPD has suppressed the truth, and it has now lead to deadly consequences."
(CNN's Alan Duke, Mallory Simon and Barbara Starr contributed to this report.)