The Ada County Sheriff's Office announced Wednesday that a man who died of cyanide poisoning inside a Boise, Idaho, church more than four decades ago has been identified as Dr. Mathew Francis Betkouski, an organic chemist whose background has drawn the attention of investigators examining the unsolved 1982 Chicago Tylenol murders.
Betkouski, known for decades only as the «Unknown Wanderer,» walked into Sacred Heart Catholic Church in Boise and died on Dec. 4, 1982. Authorities determined the cause was cyanide poisoning, but he carried no identification and his fingerprints produced no match. The case remained open until investigators traced one of nearly 30 keys found on him to Jacksonville, Florida, where Betkouski had lived. DNA recovered from his wallet and later compared with a sample from his brother confirmed his identity.
Investigators subsequently uncovered details that drew their attention to the Tylenol case. A former colleague recalled Betkouski discussing the «perfect crime» and cyanide, while another scientist remembered him saying poison could be introduced into over-the-counter capsules. Authorities also found a map of Chicago and a bottle of sodium cyanide among belongings kept at his family's Los Angeles home. The sheriff's office stressed that the poison was not the potassium cyanide used in the Tylenol murders.
Seven people died in the Chicago area during the final week of September 1982 after taking Tylenol capsules laced with cyanide. Investigators said they could not place Betkouski in Chicago during that period and are not naming him as a suspect. Photos showed he had visited Chicago, but authorities determined they were likely taken in December 1981 and said they cannot establish that he returned when the poisonings occurred.
Betkouski disappeared from his New Mexico home on Oct. 15, 1982, and turned up dead in Boise seven weeks later after apparently changing his appearance. Dr. Park Dietz, a forensic psychiatrist consulted during the original Tylenol investigation who reviewed the evidence gathered on Betkouski, offered a stronger assessment than the sheriff's office. «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. He added that groups of forensic psychiatrists, psychologists and criminal profilers who were anonymously presented with information about Betkouski overwhelmingly considered him a viable suspect.
The Ada County Sheriff's Office has turned its findings over to investigators in the Chicago area and is seeking information about Betkouski's movements and communications in 1982. «This isn't over,» Ada County Sheriff Matt Clifford said, signaling that the inquiry remains active.