After helping government forces break the Islamic State's grip over a strategic town just south of Baghdad on Saturday, Shiite militias decided it was time for payback.
A witness saw the fighters, dressed in green camouflage uniforms, scream and swear at members of the Islamist group as they kicked and struck them with rifle butts in Jurf al-Sakhar.
As the angry crowd of militiamen around the unarmed militants swelled, shots rang out. The three men lay soaked in blood in the dirt with gunshot wounds to the head.