My FBI neighbor, pre 9/11, had to leave the Army Reserve to be an agent. The stated reason was it may present a conflict of interest, or command influence on the military side, since the FBI is the only agency with nationwide criminal investigation powers. Everyone else is jurisdiction limited in some way. But the FBI can take lead on any military crime. Obviously that wasn't deemed a strong argument post 9/11. Makes me wonder though. Can NCIS be Reservists? Back in the day, NIS could not, for the reason above.
