Gregory Ulas Powell was an American criminal who kidnapped Los Angeles Police Department Officers Ian Campbell and Karl Hettinger on the night of March 9, 1963. Assisted by accomplice Jimmy Lee "Youngblood" Smith, Powell took the officers to an onion field near Bakersfield, California, where Officer Campbell was fatally shot. Powell was infamously known as the "Onion Field" Killer, when the story was depicted in Joseph Wambaugh's 1973 non-fiction book, "The Onion Field".