a person who finds (an object) by accident

one who discovers a thing

a person, ship or small, fast plane, sent out to get information about the enemy; a member of an organization training boys in character, developing self-reliance, discipline and social awareness

person who is searching, investigating

a person who tries to set secret information, especially about military affairs of other countries; a person who keeps a secret watch on the movements of others

person who secretly finds out about another's business

a man who guards property, especially at night

guard