bloodhound

noun3

1. •
   A large scenthound famed for its ability to follow a scent many days old, over vast distances. This dog is often used as a police dog to track missing people, fleeing suspects, or escaped prisoners.

   • Someone stole our bloodhounds, but we got the backup bloodhounds to chase the first tier of bloodhounds. — 2007
2. •
   (informal, figurative) A detective or other person skilled at finding people or clues.
3. •
   (no longer used) A bloodthirsty person.