Weapon 1d6 physical
The inmate is a monster added in the Convict patch, implemented in UnNetHack, DynaHack, dNetHack, Slash'EM Extended, and SlashTHEM. The inmate is the Convict quest quest guardian.
Despite their name and status, inmates do not count as prisoners who can be freed to raise your alignment record.
Reference: Karl Garrison's Convict Patch