The Federal Bureau of Investigations may use fake identities on social networks to investigate criminal activities, according to a redacted FBI document acquired by digital rights advocacy group Electronic Frontier Foundation.

Specifically, the 33-page confidential presentation says undercover operations are helpful for communicating with suspects and targets of crime, gaining access to private information, and mapping social networks. However, the presentation expresses concern that undercover use may be complicated by the court's decision in the trial of Lori Drew, who was acquitted of cyber-bullying a girl who later committed suicide, and that violations of terms of service by not using their own name can render access unauthorized.

The presentation instructs agents to investigate all witnesses on social networking sites, advising its own witnesses not to discuss cases and be careful about what they post online.

In general, the document, a presentation from the FBI's computer crime and intellectual property section, details how federal agents should gather and use evidence found on social networks like Facebook, MySpace, and LinkedIn.

The presentation, apparently given in 2009 by computer crime deputy chief John Lynch and trial attorney Jenny Ellickson, informs agents that some information on social networks might be available publicly, some might require undercover operations, and still other information may be acquired through requests from social network companies themselves under the Electronic Communications Privacy Act.

According to the presentation, Facebook is "often cooperative" with law enforcement emergency requests for information, while MySpace requires law enforcement to provide a search warrant to see private messages less than 181 days old. Twitter, meanwhile, is apparently even less helpful than MySpace, as the presentation notes it has no contact number for law enforcement to call, only retains the last log-in IP address, has no guide for law enforcement, and will not produce data without a warrant or subpoena.

The presentation notes that evidence gathered from social networks can be helpful to reveal personal communication, establish motives and relationships, provide location information, prove and disprove alibis, and establish the existence of a crime or criminal enterprise.

The presentation also details the history and use of social networks worldwide, listing which social networks are popular in which parts of the world and how social networking sites in the United States match up against other heavily visited Web sites.

Have a comment on this story? Please click "Discuss" below. If you'd like to contact Dark Reading's editors directly, send us a message.