Is Iran Covering Up Missile Take Down of Civilian Plane?

Is Iran engaging in a massive cover-up? That's what the world wants to know after Iran reportedly sent bulldozers to clear the wreckage of the civilian plane it allegedly shot down. CBS News Senior Foreign Correspondent Elizabeth Palmer visited the crash site and said there were no guards there and no one tried to stop her from coming in. She said there were people all over the crash site and some were looking for things to take from it. An expert says this hinders the investigation.