"Alfred Hitchcock Presents" Lamb to the Slaughter (1958)

Mary Maloney is a devoted wife and an exceptional housekeeper. One day, her husband, the police chief, announces that he wants a divorce because he has met another woman. Mary is quite angry and kills him with a blow from a frozen leg of lamb. She calls the police and provides and alibi for herself with the story that she'd been out to the store when the murder took place. The investigating officer, Lieutenant Noonan, is further frustrated when he cannot to find the murder weapon. Knowing of the long and hard hours spent looking into the case, Mary invites Noonan and the other investigators for a bite to eat. They dig into Mary's leg of lamb and Noonan still thinking about the missing murder weapon says "For all we know, it might be right under our very noses."