Ideas how it could work:
• Open a menu (inside justice menu?) to create a bounty. Preferably this menu could be opened from whatever screen you are in when you learn about a crime. Like from a name in a witness report [press B to create a bounty].
• Select from a searchable list of known (to the fortress) living historical figures
• Add a reward options:
• • Could be a specific item like a masterwork gold axe chosen from fortress stocks, making item reserved
• • $1000 worth of trade goods
• • 500 fortress coins which the game could interpret as whatever that value would be traded
• • Eventually real money, and maybe some social reward like residency/citizenship for outsiders
• Select conditions for bounty reward:
• • Dead, alive or either
• • Must return with a head, or other body part
• • Maybe return stolen items
• Then 'publish' the bounty, the fort sheriff could make the bounty known, a messenger could possibly spread the news to other settlements
• Then based on the details people start going for it:
• • If word has spread through rumors or messengers Monster Hunters and/or Bounty Hunters* from outside the fortress could start showing up to pursue.
• • If it's a beast that killed people in the caverns then left the map Monster Hunters in your fort could leave the map through the caverns in pursuit.
• • People would be basically the same but pursued over land.
• • Dwarves with the needs wandering, fighting, practicing a martial art, acquiring something (greed) or doing something exciting could take up the challenge. Go grab weapons and leave the map in pursuit. Filling the need if they return.
• • If your reward is too low, or the bounty too dangerous (based on reputation?) nobody will peruse it and you'll need to change it.
• Eventually someone shows up with a captive or a body part and meet with the sheriff.
• Bounty is paid, Bounty Hunter goes to the tavern to drink and brag
• Captive is put in jail or executed OR
• You have a monster/persons head to dispose of
Other notes:
• The same system could be used by player villains to kidnap/assassinate people
• could be used to put a bounty on artifacts so you can have outsiders stealing for you
*I'd lean towards making Bounty Hunters a separate thing, since Mercs are "individuals who takes part in military conflict for personal profit, is otherwise an outsider to the conflict" not solo acting law enforcement. Though Mercs should take up bounties given the opportunity.