The phrase "murder weapon" refers to an object or tool that was used to cause someone's death intentionally or unlawfully.
Sentences with «murder weapon»
You have to dispose of bodies, cover up blood stains, hide murder weapons, and more! (theswitcheffect.net)
You peel by rubbing, though be warned — they look like murder weapons. (bbcgoodfood.com)
The police had found the alleged murder weapon, which was understood to be a piece of wood, hence, the belief that she beat her mother to death. (parentherald.com)