My philosophy has been this: If you know the money was not given out to a customer, and there is no way a package from the Fed was short, then your only alternative is that the money was taken by an "insider", be it the teller that is short or a co-worker. Last year, we had 3 situations where tellers were short a large amount, and after a thorough review of their work, there was no way it could have been given to a customer. In 2 of these cases, multiple packages were missing bills. Nothing could be proven, but a SAR was filed in each case, and our investigation concluded that there had to be insider involvement in each shortage...hope this helps.