Untraceable (2008)

"A cyber killer has finally found the perfect accomplice: You."

Special Agent Jennifer Marsh works in an elite division of the FBI dedicated to fighting cybercrime. She thinks she has seen it all, until a particularly sadistic criminal arises on the Internet. This tech-savvy killer posts live feeds of his crimes on his website; the more hits the site gets, the faster the victim dies. Marsh and her team must find the elusive killer before time runs out.