Federal agents pose as Facebook friends to nab criminals

U.S. law enforcement agents are infiltrating social networks to gather information about suspects and track down criminals who prey on other Internet users or break common laws.

The AP reports that, according to internal Justice Department documents, the FBI and other law enforcement agents are logging on with fake identities to converse with suspects or suss out personal relationships or peruse photos and videos.

Investigators can even check suspects' alibis by comparing statements with Tweets and Facebook updates.

The Electronic Frontier Foundation posted the documents on its website today. One document detailed how IRS employees use social networking sites and other tools including Google Street View to investigate taxpayers. The IRS, however, prohibits employees from using fake accounts to gather the information.

Social networks are fertile ground for criminals. Sex offenders have flocked to sites such as Facebook and MySpace to find young users. Agents started monitoring AOL and MSN chat rooms a decade ago. But as more and more people join the social networking sites and maintain detailed profiles about their lives, it has become increasingly easy to track people--whether they are guilty of a crime or not.

A former U.S. cybersecurity prosecutor, Marc Zwillinger, said investigators should be able to go undercover in the online world the same way they do in the real world. But there should be limits, he told the AP.

Keeping up with requests for information from law enforcement officials has become a huge job for the likes of MySpace and Facebook. Those companies employ teams of people to keep up with such requests from authorities from around the world.

EFF says it will post more documents about how other agencies use social networking tools as they receive them.