1. A police investigation to determine the perpetrator
   - detection, detecting, detective work

1. Watch, observe, or inquire secretly
   - spy, stag, snoop

Type of: monitor, police investigation, police work, supervise

Encyclopedia: Sleuth

• irresponsible
• irresponsibleness
• irresponsibly
• irresponsive
• irretrievable
• irretrievably
• irreverence
• irreverent
• irreverently
• irreversibility
• irreversible
• irreversible process
• irreversibly
• irrevocability
• irrevocable
• irrevocableness
• irrevocably
• irrevokable
• irridenta
• irridentism
• irridentist
• irrigate
• irrigation
• irrigation ditch
• irritability