

The 20-year-old man who authorities say went on a violent shooting rampage in Orange County, killing three people and then himself, was described as a "loner" and "gamer" who "spent a lot of time alone in his room playing video games."

Orange County Sheriff's spokesman Jim Amormino said investigators do not know a motive for what set off Ali Syed. He left "no evidence, no note, no nothing that would explain this very bizarre, violent behavior," Amormino said.

At a news conference Wednesday afternoon, Amormino also identified the woman who was shot and killed at Syed's home as Courtney Aoki, 20, of Buena Park.

PHOTOS: Shootings at multiple locations in O.C.

Despite rumors that she might be employed as a stripper, Amormino said investigators have not confirmed that and said they are still trying to determine her occupation, how she met Syed and why she was at his home.

"There's still a lot of work to do in this case," Amormino said.

Syed, who had no criminal record, lived with his parents in Ladera Ranch. His parents called 911 about 4:45 a.m.

MAP: Orange County shootings

"We were asleep, we heard something," Syed's father told a 911 operator in a call released by authorities. "It sounded like a gunshot."

Syed left in an SUV, authorities said, and committed a series of violent carjackings in Tustin and Santa Ana that left two people dead and three others wounded. Syed killed himself in Orange County, authorities said.

Amormino said an autopsy determined that Syed died of an apparently self-inflicted gunshot wound to the head with a 12-gauge shotgun.

TIMELINE: Deadliest U.S. mass shootings

Aoki was shot multiple times, authorities said. The body was clothed, authorities said.

Detectives had difficult identifying her, Amormino said, because she had no identification with her and no vehicle at the Ladera Ranch residence. There were no missing persons reports and the first set of fingerprints taken from the body yielded no results.

Amormino said Aoki was identified Wednesday morning after taking a second set of fingerprints, but authorities were not able to locate her mother until about 2:30 p.m. Although Aoki's mother also lives in Orange County, Aoki did not live with her, Amormino said.

Human bones in Pasadena backyard may be tied to Santeria

Autopsy may answer questions on body found in hotel water tank

O.C. shootings: 'I think somebody's shot,' suspect's mom tells 911

— Kate Mather

Top photo: Jim Amormino, Orange County sheriff's spokesman, gives updated information on the shooting victims from Tuesday's rampage during a news conference outside the Tustin Police Department. Gina Ferazzi / Los Angeles Times

Middle Photo: Courtney Aoki. Credit: Orange County Sheriff's Department