In NYPD they actually had our S&W handcuff serial numbers locked away somewhere. When we used to watch prisoners in the hospital or transport them a lot of times we would just exchange handcuffs with the next cop, leaving the original cuffs on the guy. Years later I was notified that my cuffs were caught running down the street in Brooklyn connected to some criminal. I worked in Harlem up in Manhattan. They were ready to give me the 3rd degree when I told them that what we do during prisoner exchanges. They tried to tell me cuffs were like guns and mace, serialized. I said, OK then I want my cuffs back. Never got the cuffs back.