A recent New York Times blog post highlighted the dilemma of whether or not Twitter messages, Facebook updates, and emails are protected from access by law enforcement the same way personal telephone calls and written letters stored in a person's home. The current answer is that they are not. Our social life via social media is not within our means to control and can work against us.
This article appeared on the same day a document surfaced in the Dr. Robert G. Green papers at the University of Minnesota Archives that offered another perspective on law enforcement's use of social activities to track criminal behaviors.
Dr. Green was a bacteriologist in the Medical School. His primary research focused on the relationship between viruses and cancer in animal populations. He directed the Minnesota wildlife disease investigation and for a brief time served as chair of bacteriology prior to his death in 1947.
In his papers he kept a FBI wanted persons mailer. The person in question was William Dainard, as know as William Mahan, in connection with the 1935 child abduction and ransom of George Weyerhaeuser, heir to the Weyerhaeuser timber company.
The mailer was part of a national attempt to locate Dainard. Dr. Green received a copy as a bacteriologist due to the fact that Dainard was likely seeking treatment for a venereal disease. In this case, the FBI used Dainard's social activities, and subsequent social disease, against him in an effort to track him down.
See a copy of the FBI mailer below. Note the stamped "May Seek Venereal Treatment" under the mug shots.