ARLINGTON HEIGHTS, IL — A new documentary premiering Friday will examine whether a chemist found dead in an Idaho church could have been connected to the 1982 Tylenol murders, which claimed seven lives, including three members of a family who took capsules from the same bottle in Arlington Heights.
But the possible connection remains unproven with disagreement among people who worked on the original investigation.
"Unmasking the Tylenol Killer," the first feature-length documentary from "Unsolved Mysteries," will stream free on The Roku Channel beginning Oct. 9. Directed by franchise co-creator Terry Dunn Meurer, the 88-minute film follows Ada County sheriff's Detective Tim Cooper's investigation into the man known for decades as the "Unknown Wanderer."
Authorities announced last month that the man was Dr. Mathew Francis Betkouski, an organic chemist who died from cyanide poisoning inside Sacred Heart Catholic Church in Boise on Dec. 4, 1982.
As Patch previously reported, investigators identified him through an engraved key, property records and a DNA comparison with his surviving brother. His background raised questions about a possible connection to the Tylenol poisonings, but Ada County authorities stopped short of naming him a suspect.
Questions About The Evidence
The Chicago Tribune, in reporting published by the Daily Herald, cited multiple law enforcement sources who said Illinois authorities had compared Betkouski's DNA with profiles recovered from poisoned Tylenol bottles and found no match.
The report also said the original task force examined the Idaho death in 1982 without establishing a connection. Those findings do not establish who committed the poisonings.
Two other gaps remain: Investigators have not placed Betkouski in the Chicago area when the capsules were contaminated, and cyanide recovered from his belongings differed from the compound used in the murders.
Photos investigators initially thought might show a 1982 Chicago visit were later believed to have been taken in December 1981. The bottle found among his belongings contained sodium cyanide; the Tylenol victims were poisoned with potassium cyanide.
Jeremy Margolis, a former federal prosecutor who worked on the original Tylenol task force, rejected the proposed connection in an interview with Idaho News 6, calling it "utter nonsense." He argued that behavioral profiling does not establish that someone committed a crime.
In a statement reported by the station, the FBI said alleged links to the murders have repeatedly remained unsubstantiated and that it would release credible information when evidence establishes a resolution.
Psychiatrist Stands By Theory
Forensic psychiatrist Dr. Park Dietz, who consulted the FBI during the original investigation, defended his assessment in a Sept. 30 follow-up report from Idaho News 6.
Dietz pointed to Betkouski's chemistry expertise, access to cyanide and reported discussions about poisoning capsules. He argued that the different cyanide compounds did not rule Betkouski out because he had access to both.
"My opinion today is that he probably is the one who did it," Dietz told the station.
Dietz nevertheless acknowledged that investigators have not established whether Betkouski was in the Chicago area at the relevant time. Further evidence could strengthen or disprove the theory, he said.
Arlington Heights police previously told Patch they had received and reviewed Ada County's information and would continue pursuing viable leads with their law enforcement partners. The department said it had no additional information to release because the investigation remained active.
The documentary's producers say the film follows Cooper's seven-year investigation through interviews, records and evidence preserved for decades. Its argument for a possible connection has not been established as a law enforcement conclusion.
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