My thoughts exactly and that's the reason for my needing advice.
The letter does not state why he was over paid by mistake, but according to the paper attached, it looks like they miscalculated his hours. It did happen to be on his last paycheck, but I know he worked the full time he was supposed to.
I will ask for more clarification, but now I'm just wondering if this company pays ahead of time (like some of the big corps do) and then they re-adjust as actual hours are worked? I don't remember....but will get more info that's for sure.
I worked for years in large offices and never had a problem with that. But honest mistakes happen.
It could be something simple - his last paycheck may have included payment for a few days that he wasn't there, for example. Also note that if he was overpaid $ 192, make sure that that would be a post-withholding overpayment before you return it. In other words, if by the book he was overpaid $ 192, that figure might inclde taxes that were withheld, so in fact he may owe just the take-home portion of $192. Otherwise, you would be paying back taxes that were withheld (and which you never saw) which would be the employers problem.
Asking for more details is fair and costs a 37 cent stamp and five minutes of time to write a brief 4 sentence letter. Just because they made a mistake doesn't mean the payment was a mistake - they could be making a mistake now, as I said.
Asking for the details and specifics on what the accounting error was in this case is fair and acting in good faith.
Keep us posted and good luck!