Dr. Kris Mohandie, a clinical, police and forensic psychologist and an expert on violent behavior, said social media can and should be used by investigators to try to uncover clues about potentially violent individuals before they act.

“Social media investigation not only should be standard procedure for law enforcement, but maybe even mental health providers treating individuals who they have concerns about,” Mohandie said, noting such efforts can break down silos of information and paint “a more coherent picture” of that individual.

But many experts doubt that social media analysis would prove valuable in identifying potentially violent individuals and warn that poring over such material could prove an enormous waste of law enforcement officers’ time and resources.

The problem for authorities is that most of the material that Rodger posted online was “indistinguishable from thousands — maybe tens of thousands — of people who have similar anxieties, frustrations, inadequacies and anger,” said James Alan Fox, a professor of criminology, law and public policy at Northeastern University.