In monitoring social media, most local police forces lag U.S. intelligence agencies, which despite their vast surveillance networks still struggle to prevent attacks such as the 2013 Boston Marathon bombing, reported Reuters.
The National Security Agency had raw intercepts pointing to a person matching the 2009 "underwear bomber's" description, but failed to stop him from boarding a plane.
The Department of Homeland Security monitors about 100 social media sites, but there are restrictions that keep their agents from sharing all the information that they collect directly with local law enforcement.
Social media monitoring by police tends to be reactive: analysts hit the Internet when someone phones in a tip. Investigators use social networking sites to identify victims, look for witnesses and perpetrators, generate leads or search for evidence in the aftermath of a crime.
"Most of the stuff, honestly, we get is when people send it to us," said Los Angeles Police Department spokesman, Commander Andrew Smith.
That's not to say there have not been some successes. The LAPD, which employs around 40 people to monitor social media manually, uses software from a startup called PredPol Inc, which stands for predictive policing. The software analyzes LAPD and other internal police databases to identify crime-ridden areas and determine the best times to patrol.
PredPol marketing manager Benjamin Hoehn said crime dropped around 20 percent within 10 months of deploying the system in Modesto, California, in January.
The LAPD is also exploring the use of Geofeedia Inc, which incorporates user-location data as it crawls through sites from Twitter and Facebook to Google Inc's (GOOGL.O) YouTube and Yahoo Inc's (YHOO.O) Flickr.
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