California shooting: Sheriffs never saw menacing videos before rampage

But by the time they arrived, officers confirmed their son had gone on a rampage.

Sheriff's deputies had visited Rodger last month to check on his mental health but hadn't seen online videos in which he threatens suicide and violence even though those recordings were what prompted his parents to call authorities.

By the time law enforcement did see the videos, it was too late: The well-mannered if shy young man that deputies concluded after their visit posed no risk had gone on a deadly rampage stabbing and shooting six people to death before taking his own life Friday.

The sheriff's office said Sunday they were "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, institutionalisations or serious crimes.