GOLETA, Calif. (AP) -- The threats of suicide and violence captured in Elliott Rodger's online videos were unsettling, even terrifying.
In one, he stares icily into the camera, despairs over his hollow romantic life, then delivers a dark promise: "That's a problem that I intend to rectify. I, in all my magnificence and power, I will not let this fly."
His parents said they were so concerned that they called police. Officers who showed up at Rodger's doorstep for a mental health check in April, however, found a well-mannered if shy young man that they concluded posed no risk.
They hadn't seen the videos, and by the time law enforcement had, it was too late: Rodger had gone on a deadly rampage.
The sheriff's office "was not aware of any videos until after the shooting rampage occurred," Santa Barbara County Sheriff's Office spokeswoman Kelly Hoover said.
Sheriff Bill Brown has defended the officers' actions, but the case highlights the challenges that police face in assessing the mental health of adults, particularly those with no history of violent breakdowns, institutionalizations or serious crimes.
"Obviously, looking back on this, it's a very tragic situation and we certainly wish that we could turn the clock back and maybe change some things," Brown told CBS' "Face the Nation" on Sunday.
"At the time deputies interacted with him, he was able to convince them that he was OK," he said.
It's not clear why the sheriffs did not become aware of the videos. Attorney Alan Shifman said the Rodger family had called police after being alarmed by YouTube videos "regarding suicide and the killing of people" that Elliot Rodger had been posting.
Doris A. Fuller, executive director of the Virginia-based Treatment Advocacy Center, said California law has provisions that permit emergency psychiatric evaluations of individuals who pose a serious threat, but that was never triggered.
Rodger's family has disclosed their son was under the care of therapists.
"Once again, we are grieving over deaths and devastation caused by a young man who was sending up red flags for danger that failed to produce intervention in time to avert tragedy," Fuller said in a statement.
"In this case, the red flags were so big the killer's parents had called police ... and yet the system failed," she said.
Rodger, writing in a manifesto, said he was relieved his apartment wasn't searched because deputies would have uncovered the cache of weapons he used in the beach town rampage Friday in which he killed six people and then, authorities say, himself.
He posted at least 22 YouTube videos. He wrote in his manifesto that he uploaded most of his videos in the week leading up to April 26, when he originally planned to carry out his attacks. He postponed his plan after catching a cold.
Because many of the videos were removed from YouTube then re-added in the week leading up to the killings, it's unclear which of the videos alarmed his family, or whether others were reported that were not uploaded again.
He voices his contempt for everyone from his roommates to the human race, reserving special hate for two groups: the women he says kept him a virgin for all of his 22 years and the men they chose instead.
At least two other people who saw Rodger's videos before Friday compared him to a serial killer, through a message board on a bodybuilding website and the social network Reddit.
The rampage played out largely as he sketched it in public postings, including a YouTube video where he sits in the BMW in sunset light and appears to be acting out scripted lines and planned laughs.
"I'll take great pleasure in slaughtering all of you," the son of a Hollywood director who worked on "The Hunger Games" says in the video posted Friday and taken down by YouTube Saturday with a message saying it violated the site's terms of service.
Brown told CNN on Sunday that investigators are close to having a "pretty clear picture of what happened."
The first three killed Friday were male stabbing victims in Rodger's own apartment whose names have not been released, Brown said Saturday. Then, at about 9:30 p.m., the shooting rampage began.
Deputies found three semi-automatic handguns along with 400 unspent rounds in his black BMW. All were purchased legally.
Associated Press writer Oskar Garcia in Honolulu contributed to this report.