Police Seek Clues in Social Media

Police departments have little legal recourse against people who threaten violence against their officers, but they are aggressively monitoring social media in hopes of identifying dangers and thwarting violence.

A warning from Baltimore County Police officials, who learned about an Instagram post that suggested Ismaaiyl Brinsley planned to kill police officers as revenge for the deaths of Michael Brown and Eric Garner, came too late to stop the fatal shooting of two New York Police Department officers. Still, police departments increasingly are monitoring Twitter feeds, Facebook posts, and Instagram threads to pick up and investigate threats made against their officers. Law-enforcement experts say that social media can serve as a sort of early-detection system for trouble, and help authorities get a handle on situations before they turn violent.