Local law enforcement is getting the kind of technological boost that used to be limited to three-letter agencies, thanks to Web-based software services that mine social media for intelligence. At last month's International Association of Chiefs of Police (IACP) conference in Philadelphia, LexisNexis showed off a new tool it will bundle with its research service for law enforcement agencies—one that will help them "stake out" social media as part of their criminal investigations.

Called Social Media Monitor, the cloud-based service will watch social networks for comments and activities that might offer clues to crimes in the physical world. With direct connections into a variety of social media services' feeds, it will help police plow through Twitter and Facebook in search of evidence that could lead to arrests.

Social media is already a major tool for police departments. Some city police departments, such as the Boston Police Department, have integrated monitoring of social media into their Real Time Crime Centers (RTCCs)—operations that have been aided by federal funding in a number of large cities. And because criminals often use social media themselves (to their own detriment), social media monitoring is paying off. For example, in 2011 analysts at Cincinnati's RTCC were searching the social network connections of suspects for one crime and found video of an armed robbery posted to a Facebook page by one of the perpetrators.

It’s not just a big city phenomenon. A poll of 1,200 law enforcement officers conducted by LexisNexis found that four out of five law enforcement officers use social media as part of their investigations. More than three-quarters of those who don't use social media now plan to start using it within the next 12 months.

LexisNexis' Accurint for Law Enforcement is already something of a social network of its own. That service is a sort of LinkedIn for law enforcement agents that provides a way to network and identify people with expertise at other levels of law enforcement. It also allows for access to public records about individuals and businesses that law enforcement can use to verify identities, locate suspects and their assets, and discover links between people that may not show up on their Facebook page. The addition of Social Media Monitor adds just another layer of "big data" for investigators to mine.

Social Media Monitor is provided by an Atlanta firm called Digital Stakeout. The software-as-a-service is actually an intelligence database platform built to comply with the Department of Justice's 28 CFR part 23, the federal government's regulations on criminal intelligence information systems. And much like big data analysis systems employed by the NSA and other federal agencies, Digital Stakeout does a lot more than watch for someone to tweet "LOL just robbed a bank YOLO."

Digital Stakeout pulls data and metadata directly from Twitter's "firehose," as well historical data from Twitter. The system taps into Facebook posts and comments, Google+ and YouTube, Instagram, and other social media "big data" feeds. It performs a variety of rules-based processing on the data live from the source—including some proprietary natural language analytics that can look for thousands of combinations of words within feeds that would indicate an emergency, such as a shooting in progress. Digital Stakeout includes sentiment analysis features to monitor the general mood of postings and pick up potential threats of violence. The system can even leverage geographic metadata in posts to allow a variety of searches based on location.

Digital Stakeout isn't alone in its effort to bring social media analytics to law enforcement. The Boston Police Department uses Social Media Command Center, another Web-based application from Catonsville, Maryland-based Inttensity. And other "big data" companies that have specialized in intelligence products for defense and intelligence customers, such as Palantir and BrightPlanet, are now targeting local law enforcement agencies as a new potential pool of customers.