More than 40 years after a mysterious man died from cyanide poisoning inside an Idaho church, investigators have identified him as an organic chemist whose background has raised questions about a possible link to the unsolved 1982 Chicago Tylenol murders.
The man known for decades as the “Unknown Wanderer” was Dr. Mathew Francis Betkouski, the Ada County Sheriff’s Office in Boise announced Wednesday. Investigators said Betkouski had a history of discussing cyanide and poisons.
Authorities said they have found no evidence placing Betkouski in Chicago during the final week of September 1982, when seven people died after taking cyanide-laced Tylenol capsules. Investigators are not identifying him as a suspect.
Forensic psychiatrist Dr. Park Dietz speaks during a news conference Wednesday at the Ada County Sheriff’s Office in Boise, Idaho, about the “Unknown Wanderer,” now identified as Dr. Mathew Francis Betkouski. Betkouski’s image appeared beside Dietz on a video screen as officials discussed his possible connection to the 1982 Tylenol murders. (Ada County Sheriff’s Office / Facebook)
Forensic psychiatrist Dr. Park Dietz, who worked as a consultant during the original Tylenol investigation and later reviewed evidence collected about Betkouski, offered a more pointed evaluation.
“It’s an extraordinary thing to have been around at the beginning in 1982, and now today in 2026, to see very likely closure.”
Dietz said teams of forensic psychiatrists, psychologists and criminal profilers were anonymously given information about Betkouski. An overwhelming majority concluded that he was a viable suspect in the Tylenol case.
Betkouski died Dec. 4, 1982, after entering Sacred Heart Catholic Church in Boise. Authorities determined that cyanide poisoning caused his death, but he had no identification, and fingerprint checks failed to produce a match.
Investigators in Idaho later uncovered a series of details that prompted them to examine whether Betkouski could have had a connection to the Tylenol murders. (Courtesy of Netflix © 2025)
The identity mystery remained unsolved for decades. Investigators eventually traced one of nearly 30 keys found on Betkouski to Jacksonville, Florida, where he had lived. DNA taken from his wallet was compared with a sample from his brother, helping confirm who he was.
The subsequent investigation uncovered additional details that drew authorities’ attention to the 1982 Tylenol poisonings.
According to investigators, a former colleague remembered Betkouski talking about the “perfect crime” and cyanide. Another scientist recalled Betkouski saying poison could be placed inside over-the-counter capsules.
Authorities also discovered a map of Chicago and a bottle of sodium cyanide among belongings stored at Betkouski’s family home in Los Angeles. Investigators emphasized that the substance was not the potassium cyanide used in the Tylenol murders.
Ada County Sheriff Matt Clifford speaks during a news conference Wednesday in Boise, Idaho, identifying the so-called “Unknown Wanderer” as Dr. Mathew Betkouski. Officials said Betkouski may have a possible connection to the notorious 1982 Tylenol murders. (Ada County Sheriff’s Office / Facebook)
Photographs confirmed that Betkouski had visited Chicago, but investigators believe they were probably taken in December 1981. They said there is no evidence establishing that he returned to the city when the Tylenol poisonings occurred.
Betkouski vanished from his home in New Mexico on Oct. 15, 1982. Seven weeks later, he appeared dead in Boise, apparently after altering his appearance.
Officials have shared their findings with investigators in the Chicago area and are asking the public for information about Betkouski’s movements and communications during 1982.
“This isn’t over,” Ada County Sheriff Matt Clifford said.
