The problem that we have here is the fundamental use of tools whose sole purpose is to learn and to prevent accidents (black box recorders and/or forensic analysis ) being usurped by criminal probes and thus taken out of the hands of the crash investigators.
Personaly I would rather await the decoding and analysis of the data before handing it over to a criminal investigation. And then only under defined aviation law of what constitutes criminal negligence in the operation of a flight for hire.
In the case of suspected simple or compound negligence then I would prefer that no interference with the investigation until after it has been fully completed (I'll admit that there needs to be a definition of what fully completed means)
I'm kind of hoping that defined aviation law in my imaginary image doesn't assign criminality to a pilot having a mental block that day on a specific flight but does have to consider past history.
I'll support the interests and expertise of the Flight Safety Foundation in this subject to sort out a better compromise