U.S. police assess rise in threat tips after 3 mass killings

LOS ANGELES — It had all the makings of a massacre. Six guns, including a Colt AR-15 rifle. About 1,000 rounds of ammunition. A bulletproof vest. And an angry Southern California man who threated to kill his co-workers at a hotel and its guests.

But a concerned colleague intervened, alerting authorities who arrested 37-year-old Rodolfo Montoya, a cook at the Long Beach Marriott hotel, the next day and discovered the arsenal where he lived in a rundown motor home parked near industrial buildings.

In the weeks after three high-profile shootings in three states took the lives of more than two dozen people in one week in August, law enforcement authorities nationwide reported a spike in tips from concerned relatives, friends and co-workers about people who appear bent on carrying out the next mass shooting.

Some of those would-be shooters sent text messages to friends or posted on social media that they hoped to oneup previous mass shootings by killing more people.

The reasons for the increase in tips and heightened awareness of thwarted mass shootings vary, law enforcement officials said.

In some cases, it’s the “contagion effect” in which intense media coverage of mass shootings leads to more people seeking to become copycat killers. In other cases, it’s a reflection of the general public being more aware of warning signs when a friend or relative or coworker is in an emotional crisis — and more willing to tip off police.

On average, the Federal Bureau of Investigation receives about 22,000 tips about potential threats of violence weekly. That volume increased by about 15,000 following the high-profile shootings during the first week of August in Gilroy, Calif.; El Paso, and Dayton, Ohio, that killed 34 people and wounded nearly 70.

Mass shootings tend to plant the idea of carrying out a rampage or at least encourage the idea in potential mass shooters, each seeking notoriety or striving to “out-do” others with higher death tolls, said sociologist James Densley, a criminal justice professor at Metropolitan State University in St. Paul, Minn., who studies mass shootings and the people who perpetrate them.

And the general public in turn becomes more aware of the possibility of mass shootings, heightening people’s willingness to speak out if a friend, relative or co-worker appears to be in the midst of a crisis and plotting carnage, Densley said. In addition, the media focuses not only on the actual shootings, but also on those that are foiled.

The reason? Mass shootings remain rare events and there’s no one basic profile for the attackers. The demographics of school shooters and their motivations are vastly different from someone who carries out carnage in a place of worship. The same holds true for those who carry out workplace shootings.

“When it comes to thinking about the profile of a mass shooter what our research is starting to uncover is there’s not really one profile of a mass shooter,” Densley said.

But the one common thread is that there are usually warning signs in the days and weeks leading up to the shootings, with many shooters taking to social media to vent outrage at whatever is troubling them.