He teaches employees how to watch for the missed and mishandled warning signs that have preceded some mass shootings: co-workers who seem particularly angry, who make threatening remarks or who react inappropriately to normal workplace situations.

If an employee thinks something is “off” with a colleague, Doherty said, they are probably right. He promotes a variation on the post-9/11 vigilance motto: “Sense something, say something.”…

Doherty advises companies to provide ways for employees to report concerns anonymously and to put policies in place for handling such issues internally when possible, including meeting with employees and turning to their own security staff and others. When situations escalate, businesses can enlist firms like Hillard Heintze to interview the employee of concern or review their social media to develop a risk assessment.

The idea isn’t to get people in trouble, Doherty said, but to sound the alarm well before a crisis.