Back in the '70s, I managed a full service gas station open 24/7. Finding 3rd shift help was no easy feat. I would take what I could get and some were pretty sketchy. Never had an employee leave with the cash, but did have one clean out the vending machines that were operated by an outside company.
The vending route operator comes in one morning, opens the cigarette and candy machines and they were empty. No coins, no product. hTe locks were not tampered with.
He nor I could figure it out and he was pissed!
These were those old machines with the glass front displaying the product and under each selection was a handle attached to a metal rod that you would pull straight back towards you to release the cigarettes or candy bar of choice that would drop down to the bottom with a satisfying thud.
Well this enterprising thief, in the middle of the night, turned the machines on their tops, and all the change fell out of the coin boxes and landed on the inside tops of the machines.
He then turned the machines upright and the change fell down to the bottom where your purchased item is retrieved.
Then he took the money and bought what he could with what change he had.
Repeat over and over until everything was gone.
I didn't need to fire him. When he found out who controlled the vending routes in Detroit, he was in the wind, leaving his final pay to settle up.