Wikipeida:
In 1979, Morton Conroy, a well-known Long Island barbeque manufacturer and his wife were found shot to death at point-blank range inside a room locked on the inside. Not only was no gun found in the room, but no bullets were found in either body.It transpired that a maid who had been hired several months earlier had a brother who had died a slow and agonizing death following the explosion of a Conroy barbeque. She had taken her revenge and staged the locked-room to challenge the police, who quickly discovered the special tweezers she had used to lock the door after removing the gun from the room. The disappearance of the bullets was a far more ingenious effort, however. She had fabricated the bullets from pieces of meat and bone, honing the bone into a bullet shape and packing it and the attached meat into a shell case. At point-blank range, the bone pierced the victim's heart and shattered into tiny pieces, and the meat was dispersed into the surrounding flesh where it became practically invisible. The technique was later used in a fictional locked-room mystery published in the UK and the US.