A man who died from cyanide poisoning inside an Idaho church more than 40 years ago has been identified, and investigators say his background may point to a possible link to the unsolved 1982 Chicago Tylenol murders.
The man long known as the “Unknown Wanderer” was Dr. Mathew Francis Betkouski, an organic chemist who had spoken about cyanide and poison, the Ada County Sheriff’s Office in Boise announced Wednesday.
Investigators 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. Authorities emphasized that they 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, pictured next to Dietz on a video screen — and his possible connection to the 1982 Tylenol murders. (Ada County Sheriff’s Office / Facebook)
Dr. Park Dietz, a forensic psychiatrist who consulted on the original Tylenol investigation, reviewed the evidence collected about Betkouski and reached a more pointed conclusion.
“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 groups of forensic psychiatrists, psychologists and criminal profilers were presented with information about Betkouski without being told his identity. The experts overwhelmingly regarded him as a viable suspect.
Betkouski died Dec. 4, 1982, after entering Sacred Heart Catholic Church in Boise. Officials determined that cyanide poisoning caused his death, but he had no identification, and fingerprint searches produced no match.
Investigators in Idaho subsequently uncovered several details that drew their attention to the Tylenol case. (Courtesy of Netflix © 2025)
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The identity mystery lasted for decades. Investigators eventually traced one of nearly 30 keys found in his possession to Jacksonville, Florida, where Betkouski had lived. DNA taken from his wallet and compared with a sample from his brother helped confirm who he was.
As investigators examined Betkouski’s history, they found several details that prompted comparisons with the Chicago Tylenol murders.
One former colleague remembered Betkouski discussing the “perfect crime” and cyanide. Another scientist told investigators that Betkouski had said 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 his family’s home in Los Angeles. Investigators noted that the chemical was not the potassium cyanide used in the Tylenol killings.
Ada County Sheriff Matt Clifford speaks during a news conference Wednesday identifying the so-called “Unknown Wanderer” as Dr. Mathew Betkouski in Boise, Idaho. Officials said Betkouski may have a possible link to the infamous 1982 Tylenol murders case. (Ada County Sheriff’s Office / Facebook)
Photographs confirmed that Betkouski had been to 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 was found dead in Boise, apparently after changing his appearance.
Authorities have shared their findings with investigators in the Chicago area and are asking anyone with information about Betkouski’s movements or communications in 1982 to come forward.
“This isn’t over,” Ada County Sheriff Matt Clifford said.