Break the law and your new Facebook 'friend' may be the FBI

The Feds are on Facebook. And MySpace, LinkedIn and Twitter, too. Law enforcement agents are following the rest of the Internet world into popular social-networking services, even going undercover with false online profiles to communicate with suspects and gather private information, according to an internal Justice Department document that surfaced in a lawsuit.

The document shows that U.S. agents are logging on surreptitiously to exchange messages with suspects, identify a target's friends or relatives, and browse private information such as postings, personal photographs and video clips. Among the purposes: Investigators can check suspects' alibis by comparing stories told to police with tweets sent at the same time about their whereabouts. Online photos from a suspicious spending spree — people posing with jewelry, guns or fancy cars — can link suspects or their friends to crimes. The Department of Justice document also reminds government attorneys taking cases to trial that the public sections of social networks are a "valuable source" of information on defense witnesses.

"Knowledge is power," says the paper. "Research all witnesses on social networking sites."