Innocent Bystander is a common Creature — Goblin Citizen card from Murders at Karlov Manor (MKM), collector number 133. Current market price: $0.08 (foil $0.03), TCGplayer market prices via Scryfall.
Whenever this creature is dealt 3 or more damage, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")