If the arrest was recent
Start with the county jail
Because Alaska is a unified system, a person arrested anywhere in the state is booked into a state DOC correctional facility (pretrial), not a county jail, so the SAME VINE search and DOC facilities apply to a recent arrest and to a sentenced person.
There are no county-run jail rosters to check.
Alaska DOC does contract with about 15 small local 'community jails' (run by some city police departments) for short-term holds; those are still part of the state system.
Use VINE, or call the specific DOC facility, to confirm a recent booking.
No county jail rosters exist in Alaska because there are no county jails; the state DOC (searchable through VINE) holds everyone, including pretrial detainees.