If you're ever involved in a serious crime, you can expect the police to subpoena your Facebook account. Here 's what Facebook sends them.
The Boston Phoenix has a fascinating story up about the unusually tech-centric hunt for Craigslist Killer. In the course of reporting, the paper's reporters came across something they, and the general public, had never seen before: The full results of a Facebook subpoena.
This is what Facebook sends to the police when they (or rather, a judge) asks nicely enough (view the entire file here):
A lot of paper
Three months of Facebook data, in this case, adds up to 71 printed pages
All your wall posts and shares
This is obvious, since these are more or less public anyway. Also, the subpoena was executed before Facebook Timeline and News Feed came out. A file compiled today would probably be a lot longer (and harder to read).
All your friends (and enemies)
The file contains a list of the friends you still have as well as the ones you've deleted. Facebook, like a lot of web services, has a full memory of all your actions — the friends, the unfriends, the likes, the shares. Facebook is a million little bells that you can't unring, at least as far as police investigations go.
Source: blog.thephoenix.com