Many years ago when I worked for a bank we had an investigation by the bank inspectors as a sum of money had gone missing. We were all called in in turn to see the inspectors. If you were a member of the union you were allowed to take a union rep in with you, though the rep was not allowed to say anything except 'I think it's time for a break now' if you'd been in there a couple of hours.
The inspectors never did find the money, it turned up by it's self behind a filing cabinet about a month later, still sealed, date stamped (with the date it had gone missing) and everything!