How Would I Find Someone In A County Jail In New York?

Do you know which jail they are in? If so that kind of makes it easy, but I'm guessing that you don't. Usually if you can just figure that out you can call the jail and they can give you the information. Rikers Island is notoriously bad at tracking down inmates, FYI, so if you try to call there expect it to take several phone calls and possibly hours (or days).