Dorner had vowed to kill police officers to avenge what he called his unfair termination. He was fired after accusing his training officer of kicking a suspect during a July 2007 arrest, a complaint the LAPD concluded was unfounded.
The department accused him of lying to superiors and to internal affairs investigators and forced him out in January 2009. Dorner challenged his dismissal in court but was unsuccessful.
Dorner was first named a suspect in two shooting deaths on February 3: Monica Quan, the daughter of his police union representative, and her fiance, Keith Lawrence.
Police say he killed Crain and wounded Crain's partner in an ambush on their patrol car February 7. They say he also wounded an LAPD officer who chased him in the suburban city of Corona, California.
In a manifesto announcing his planned rampage, Dorner said nothing had changed in the LAPD since its scandals of the 1990s, the Rodney King beating and the Rampart police corruption case. Those allegations have struck a chord with some who say that, despite the four killings, Dorner was seeking justice.
Shadowed by that history, LAPD Chief Charlie Beck announced Saturday that the department would re-examine its proceedings against Dorner. The review is "not to appease a murderer," but "to reassure the public that their police department is transparent and fair in all things we do," he said.