I don't know necessarily for the NTSB, but the usual standard for these safety agencies is that their work cannot and shall not be re-used in criminal or civil

I don't know necessarily for the NTSB, but the usual standard for these safety agencies is that their work cannot and shall not be re-used in criminal or civil proceedings. We'd rather find the cause and improve safety than send somebody to jail if we can't have both. It may be different in the US because Americans are so blood thirsty (e.g. they still have and use the death sentence!) but that's how such an agency is usually intended to secure co-operation that you wouldn't necessarily get if you were law enforcement.