Reply #2: No - consistent with standard NTSB policy

[hack89]

Investigations Involving Criminal Activity

In cases of suspected criminal activity, other agencies may participate in the investigation. The Safety Board does not investigate criminal activity; in the past, once it has been established that a transportation tragedy is, in fact, a criminal act, the FBI becomes the lead federal investigative body, with the NTSB providing any requested support.

http://www.ntsb.gov/abt_ntsb/invest.htm

Now if you could show where the NTSB has investigated crimes in the past, you might have something.