that the engineer missed something or operator error. help us understand what these other possibilities are. how can the engineer not be in some way responsible. >> i believe he is responsible. there's certainly a small possibility of a mechanical problem. when you've got a train going twice the maximum speed of 50 miles an hour, to me it's a no-brainer. it's intuitively obvious to the casual investigator the train was going way too fast. generally speaking that's going to be an engineer operating failure. >> so when it comes to his story, mayor, i want to get your take on this, the engineer's attorney, he spoke to abc news and right now says he has no recollection of the event. listen to hear what he said. >> he has i believe result of the concussion, he has absolutely no recollection