William P. Bosak was a 33-year-old Chicago Police Department officer killed in an ambush on March 3, 1979. He and his partner, Officer Roger Van Schaik, had just completed a traffic stop near 115th Street and May Street when 36-year-old Kenneth Allen, who reportedly resented police after a prior arrest in which his weapons were seized, opened fire. Allen first used a .45 caliber semi-automatic pistol, striking Bosak multiple times; Van Schaik, though wounded, radioed for help. Allen then returned to his car, retrieved a .30 caliber carbine rifle and continued firing before fleeing. Officer Bosak died of his wounds.

Kenneth Allen was apprehended shortly after the attack, convicted of Bosak’s murder and sentenced to death; that sentence was later commuted and he remains incarcerated serving life without parole. The killing underscored the risks officers face and drew attention to gun violence and death penalty issues.