In the event that an investigator has nothing else to go on in determining what caused a crash, you can bet your a@# that in the last few minutes of flight, the crew were concentrating rather hard on not allowing the crash to occur at all. They are less than likely to be concerned with whether or not other people figure out what happened to them if it goes badly.
If it's that serious, crew communication is going to be focused on getting the plane on the ground - that's the pilot's problem which we are paid to solve. Putting together the pieces afterwards with limited information is the Accident Investigator's problem which he is paid to solve. I'll worry about earning his paycheck after I'm on the ground with another "so there I was" story.