Shaping up to be a puzzling one. Generally consensus seems to be a "suicide by cop" case after he killed his two intended targets. But then, while he was all dressed up in the shooter regalia, James Holmes style, he didn't really seem to have a plan where to go or what to do after killing his purported relatives, and his selection of who and what to shoot and who and what not to shoot after the main killings was random, not a "kill as many as possible." And the targets seemingly not dependent on whether they did what he said, or had a car he wanted, like a "normal" carjacker. Was more like he shot if he didn't like the looks of them. If you were to judge by the targeting alone, you would guess a panicked person shooting nonsensically after committing a crime, but witness descriptions describe his extreme calm.

Santa Monica shooter John Zawahri left a remorseful farewell note to friends, mother
The three- to four-page handwritten letter was found on Zawahri's body and expressed remorse for the killing of his father and brother.

Associated Press, June 14, 2013

[....] The three- to four-page handwritten note was found on Zawahri’s body after he was shot and killed June 7 by officers on the campus of Santa Monica College, Police Chief Jacqueline Seabrooks said at a news conference.

In the note, which was conversational in tone, 23-year-old Zawahri also said goodbye to friends and expressed hope that his mother would be taken care of and receive recompense from his father’s estate.

Seabrooks said investigators believe mental illness played a role in the killings, but she didn’t give details. “We know his was a troubled life and that he experienced mental health challenges,” Seabrooks said. “We believe that his mental health challenges likely played a role in his decisions to shoot and kill both his father and his brother, to set fire to the family home, and to go on a 13-minute shooting spree spanning roughly 1.5 miles and which left five innocent people dead and three people injured.” [....]

Seabrooks said the semi-automatic weapon appears to have been built with component parts that are legal to obtain, but put together make the rifle illegal in California. She said he also modified an antique black-powder .44 revolver so that it could hold .45-caliber ammunition; it was loaded during the shooting and he carried it with him in a duffel bag. [....]