Unsolved Mysteries Debuts Feature on Tylenol Poisonings and Idaho Cold Case

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Directed by Terry Dunn Meurer, the doc streams free and explores a decades-old mystery resolved by the Ada County Sheriff's Office.

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UNSOLVED MYSTERIES will return with its first ever feature length documentary titled Unmasking the Tylenol Killer, which will stream for free on The Roku Channel starting October 9.

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Unmasking the Tylenol Killer was revealed following Unsolved Mysteries 's press conference with the Ada County Sheriff's Office where they announced the resolution of one of Idaho's longest-standing cold cases: the identity of the 'Unknown Wanderer,' an unidentified man who died inside a Boise church in 1982. The announcement also unveiled a possible connection between this case and the 1982 Tylenol poisonings, an unsolved case that claimed seven lives in the Chicago area and remains one of the most significant unsolved crimes in U.S. history. The Ada County Sheriff's Office worked closely with the Unsolved Mysteries team throughout the course of this investigation.

Directed by Terry Dunn Meurer - the co-creator of the franchise - this new documentary is described as upending the public's long-held understanding of the calculated mass murders at the heart of one of America's most enduring and perplexing cold cases.

Unmasking the Tylenol Killer premieres exclusively on The Roku Channel on October 9, 2026. The film runs 88 minutes and is in English.

In December 1982, parishioners entering a Catholic church in Boise, Idaho discovered the body of a well-dressed stranger lying between the pews. The man had died from cyanide poisoning, carried no identification, and left behind only a note signed with what proved to be a false name: William L. Toomey. Despite decades of investigation, no one could identify him. He became known simply as 'The Unknown Wanderer.'

Nearly forty years later, Ada County Sheriff's Detective Tim Cooper becomes consumed with solving the mystery that had captivated him since childhood after first seeing the case featured on Unsolved Mysteries . What begins as a quest to restore the unknown man's identity evolves into an investigation that uncovers one of the most startling developments in true crime history.

Following a trail of decades-old evidence, including a ring of mysterious keys, forensic genealogy, forgotten documents, and interviews spanning the country, Cooper finally identifies the Unknown Wanderer. But discovering his identity only deepens the mystery.

As Cooper reconstructs the Wanderer's life, disturbing details emerge. Former classmates describe a gifted but deeply troubled man fascinated by explosives and chemistry from an early age. Former colleagues recall conversations about committing the 'perfect crime,' his fixation on cyanide, and chilling discussions about poisoning over-the-counter medications. The Wanderer possessed both the scientific knowledge and access to deadly chemicals, while his increasingly erratic behavior led to repeated psychiatric hospitalizations, the loss of his career, and the collapse of his marriage.

The investigation soon uncovers an astonishing timeline. The Wanderer vanished during the exact time period of the infamous 1982 Chicago Tylenol murders, in which seven innocent people died after taking cyanide-laced capsules. Evidence places him in Chicago that year, reveals unexplained ties to the city, and uncovers maps, letters, homemade cyanide, and other artifacts hidden for decades inside his preserved childhood bedroom. Cooper also discovers suspicious cyanide deaths outside Chicago that may have been earlier experiments, suggesting the scope of the crimes may have extended far beyond what history remembers.

Through interviews with victims' families, forensic psychiatrists, retired investigators, pathologists, and the Wanderer's former friends and coworkers, the documentary assembles a compelling circumstantial case pointing to a suspect who has never before been publicly identified. Along the way, Cooper's own deeply personal journey, shaped by childhood abandonment and a lifelong determination to bring answers to families of the missing, becomes inseparable from the investigation itself.

Unmasking the Tylenol Killer chronicles an extraordinary seven-year investigation that transforms an unidentified death into a breakthrough in one of America's greatest unsolved mysteries . The film presents powerful new evidence, identifies the strongest suspect ever uncovered, and makes a compelling case for reopening the investigation in pursuit of long-overdue answers for the victims, their families, and the public.

Unsolved Mysteries is one of the highest-profile mystery series in television history – for over forty years, the team has told real stories with a real purpose: generating leads, finding answers, and helping families seek the truth. This case is the latest of over 260 crimes solved by the six-time Emmy-nominated series.

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_Originally reported by [BroadwayWorld](https://www.broadwayworld.com/bwwtv/article/UNMASKING-THE-TYLENOL-KILLER-to-Stream-on-The-Roku-Channel-20260923)._