Some colleges and police departments are starting to use software that scans social media to identify local threats, but most tips still come from members of the public.
Ikon Images/Getty Images
February 23, 2015 It's hard to know when to take violent language seriously online. But when Jonathan Hutson saw an anonymous threat to an unnamed school on Twitter, he couldn't let it go.
<iframe src="http://www.npr.org/player/embed/388449799/388520677" width="100%" height="290" frameborder="0" scrolling="no">
Who goes there? On the Bay Bridge, the new troll will want to know.
September 3, 2013 After the 1989 earthquake that shook the region, the Bay Bridge had been "protected" by a metal troll welded to the span. Some had worried that the new Bay Bridge wouldn't have its own troll. To the relief of many, it will.
NPR thanks our sponsors
Become an NPR sponsor