martin joins us from the crash site. and jonathan, i believe we are standing by to get an update on the investigation soon >> reporter: that's right, tonywe are expecting a news conference in the ntsb at 4:00 o'clock. so any minute, we will learn something. hopefully, as you mentioned, the investigators do have those two black boxes, the black box data recorders. one from the front of the train. one from the back. that hopefully will allow them to learn some information about what caused this deadly crash. tony, the big questions really out there at this point are: you know, was this caused by a mechanical error, operator error or possibly something else? maybe something with the tracks. now, the train's conductor who was injured, himself, in this derailment has said that there was an issue, possibly with the braking system. but these recorders are really significant because they can tell investigators down to the second what was going on with the air pressure in the braking system. so they will be able to tell to the one-second intervals whether there was an issue, whether the brakes did malfunction and, also, possibly, tony, whether t