Stolen Paychecks?

How would you handle an employee alleging that their paycheck was stolen from their mailbox? I deal with lost checks all the time but a supposedly stolen one is new to me.

We are showing that the original check was cashed (likely by the thief). The check copy we received doesn’t seem to be endorsed either.

Employee is insisting that we owe them their payment still and that it is not their fault that the check was stolen. Thanks all!