On Halloween night in 1974, eight-year-old Timothy O’Brien came home from trick-or-treating in Deer Park, Texas, excited to sample his candy haul. Among the treats was a Pixy Stix — one that would become infamous in American true crime history. Within hours, Timothy was dead, poisoned by cyanide.

Investigators soon discovered that the killer wasn’t a mysterious stranger slipping poison into Halloween candy. It was someone much closer to home — his own father, Ronald Clark O’Brien. His crime forever changed the way parents across the United States viewed Halloween, giving rise to decades of fear over tampered sweets.

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In 1974, 'Candyman' turned Halloween truly terrifying in Pasadena, Texas - ABC13 Houston

The Man Who Killed Halloween - Fort Worth Weekly

'Man Who Killed Halloween' still haunts holiday - Houston Chronicle

The Haunting Legacy of Ronald Clark O'Bryan, the Man Who Killed Halloween - A&E True Crime

50 years ago, a Houston killer dubbed the 'Candyman' poisoned his son's Halloween candy - KHOU

Looking into the eyes of evil: The day I covered the execution of Texas' infamous Halloween killer - Breckenridge Texan

The True Story of the Notorious Trick-or-Treat Murderer - Vice

Halloween Horrors: The Poisoning of Timothy O'Bryan - Criminal

The ex-wife of Ronald Clark O'Bryan - UPI Archives

The neighbor who accompanied condemned killer Ronald Clark O'Bryan - UPI Archives

Ronald Clark O'Bryan - Wikipedia

Timothy Marc O'Bryan - Find a Grave Memorial

Ronald Clark O'Bryan - Murderpedia

Ronald Clark O'Bryan - Alchetron

1984: Ronald Clark O'Bryan, candyman - Executed Today

THE CASE OF THE HALLOWEEN CANDY KILLER - Harris County District Clerk

Ronald Clark O'Bryan Murder Trial (1975) - KPRC-TV Collection