As far as I can tell from the database, neither Mercer Co. Sheriff or Princeton State Police would be on 42.1 MHz.
That appears to be a backup linking channel used for a few stations to intertie when phones aren't handy, or somesuch. Two base locations in the whole county, and no mobiles, in FCC licenses.
The database indicates those two are on the statewide digital system, with Princeton FD on talkgroup 5403, and I can't really tell which State Police Troop would be in your area.
Oh, and it would probably work better if you asked the question in the West Virginia forum, rather than here.