If the person had receipts, original packaging that matches serial number to the product
Then this person may have a better case then you would have if brought to civil court.
If the person doesn't have this stuff, then it's basically just your word against his.
Someone can call the cops all they want, the cop will just say that the issue has to be settled in court.
What you said can be interpreted in many ways, care to provide an example? This could be anything from an online transaction to a friend giving you a gift and anything from a $5 trinket to, well, something very valuable