@shoppingdad uh.... not trying to argue here, but surely you've heard of people being convicted on "circumstantial evidence"? Whether he was seen pocketing or not, what wasn't seen was him ringing it up at a register. So really the only question was, was the register he was supposed to use the one that was visible, or was "his" register out of sight around the corner? When you're working a register, there are rules for when/how you ring up the sale and put away the cash and which register you use.
Now at my recent job, all big bills over $20 were immediately put in a locked box under the counter. So if i reached down there with the bill, the customer wouldn't see if i put it in the box or laid it on top. But the sale would have been rung up and a receipt issued so if my drawer was $50 short it wouldn't take a secret shopper to alert management. But if I didn't ring it up and no change was needed, my disposal of the cash wouldn't be the tip-off, it would be the failure to ring up the sale.
Time to build a bigger bridge.