Whistleblowers

noun a person who provides information or assistance, especially to authorities

adjective pertaining to or serving as an informant

• The informant provided crucial information to the authorities.
• The informant spilled the beans to the cops.
• The snitch ratted out his friends to save himself.
• The informant was like a beacon of light in the dark world of crime.

noun a person who provides information to the authorities about someone else's illegal or criminal activities

• The informer provided crucial information to the authorities.
• The informer spilled the beans to the cops.
• The snitch ratted out his friends to save himself.
• The informer acted as a beacon of light in the dark world of crime.