I would make an accident report inadmissable as evidence without the verbal evidence of the chief investigator for that accident.
Why arrest members of a crew? Possibly because you fear they will quietly disappear if they know they have been negligent. Possibly to distract press attention from the fact that your own officials have been negligent. Possibly because you don't understand the principles of accident investigation. Possibly because you don't know, don't care, are throughly corrupt and want people to bribe you to have their crews released...