(CNN) -- 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.
The LAPD now says Dorner is the subject of a massive manhunt. It accuses him of killing one police officer and wounding two others, as well as killing the daughter of his police union representative and her fiance on Sunday.
In a letter addressed to "America" and provided to CNN by an LAPD source, Dorner threatens to retaliate against officers involved in his case and their families.