Rodger, 22, was responsible for a killing spree at the University of California in Santa Barbara on May 23, 2014 that left seven dead including the shooter himself. A further 13 people were injured, some of them seriously.
He is the latest disturbed young man to go on a rampage with a gun after Colorado movie theater shooter James Holmes and Sandy Hook school attacker Adam Lanza.
“All were young loners with no criminal history who went on shooting sprees, leaving devastated families in their wake,” reported the Huffington Post.
While few of the mass shooters have prior criminal records meaning the criminal justice system may have had few dealing with them, many of them share a history of social isolation, pent-up frustration and unhappiness, say experts.
“They all display deluded thinking and a lot of rage about feeling so marginalized,” James Garbarino, a professor of psychology at Loyola University Chicago, told the Huffington Post in an email.
The rareness of mass killings means it’s difficult to predict who has deadly intent. However, all of these killers displayed warning signs before they snapped.
Rodger left numerous YouTube videos and a 140-page manifesto, which was a rant against women and couples that lamented his lack of a sex life.
Rodger’s mother became alarmed about his frightening videos and alerted authorities in April. Four deputies visited Rodger shortly before the killings, but failed to view his videos, according to the Los Angeles Times.
Pinpointing a mass killer “is not an exact science. We don’t have a foolproof way of predicting” who will turn violent, said Risdon Slate, a professor of criminology at Florida Southern College, in the Huffington Post report.
However, in most of these mass shootings, there have been clear warning signs.
Lucinda Roy, a former Virginia Tech academic, recently wrote a book in which she described how she sought to get psychiatric help for 23-year-old Seung-Hui Cho more than a year before he went on murderous shooting spree on the campus, killed 27 students, five teachers, and then himself, in 2007
In the fall of 2005, when she was chair of the English department, she unsuccessfully sought help for Cho after a colleague alerted to his disturbing writings and disruptive behavior.
On repeated occasions warning signs have been missed before mass killings. They appear to be obvious with the benefit of hindsight.