How Insufficient Understanding of Web Applications Like Facebook / Twitter Can Free Criminals

Question is whether IP behind the status update originates from the home of the criminal suspect. 1. Does Facebook track the IP address behind each update or log time and user information? 2. Identifying the IP address and determining the exact location/computer which has that address at the time of an event is difficult without ISP support. 3. Criminal can either use a proxy server on his machine to send his update from a different location (which will appear as if he had updated from the location of the proxy server) or he can have an accomplice post the update on his behalf from his desired location.