In a recent survey of 1,200 law enforcement personnel, four out of five said to identify persons of interest, criminal activity, and associates connected to a person of interest.

"Cops have figured out that people put enormously detailed information about themselves online," explained Lee Altschuler, a in the Bay Area of California.

Altschuler has experience on both sides of the courtroom: when he left in 1998, he was the Chief of the Silicon Valley Branch Office of the U.S. Attorney's Office in Northern California. While working as a U.S. Attorney, Altschuler saw first hand the growing use of data when working Federal criminal cases. Today, as a defense attorney, he believes "online data use is exploding."

Altschuler sees many law enforcement agencies in medium- to large-sized cities either using social media to conduct investigations or gearing up to do so. That's because from the agencies' perspective, there is a vast harvest of information to be reaped, and there are little to no privacy rights extended to persons of interest and suspects online.