person of interest

noun1

1. •
   Someone who police have reason to believe may have a connection to a crime, or to possess important information relating to that crime, but who has not been accused or charged by authorities nor been officially deemed to be a suspect.

   • Tice denies involvement in any conspiracy. . . . Still, Morgan says Tice and "three or four other people" remain "persons of interest" in the investigation. — 2009