authorities but it gives them a lot of information. >> even looking at his digital footprint if you will is going to reveal a lot about this man, who he is, his behavior. his interest, his frustrations. >> this has been a growing area of forensics over the past ten years or so. i remember when this was first happening and terrorist groups started nibbling at social media and law enforcement was saying well, that is two-way street. there's a ton of information to be gained by that about who he's in contact with. that was true in this case, too. you looked at his twitter feet feed. that told him a lot about this guy and by having hostages speak every time the message was slightly different in each of these videos and each one gave more information about what was happening inside and his state