Investigators identified the man as chemist Mathew Francis Betkouski but have not named him a suspect in the 1982 Chicago-area poisonings.
BOISE, ID — A man whose identity remained a mystery for more than four decades after he died from cyanide poisoning inside a Boise church has been identified as Dr. Mathew Francis Betkouski, an organic chemist whose background has prompted investigators to examine possible connections to the unsolved 1982 Tylenol murders.
The Ada County Sheriff’s Office announced the identification Wednesday, bringing an answer to one of Idaho’s most enduring cold cases while opening new questions about Betkouski’s movements before his death. Authorities stressed that Betkouski has not been officially named a suspect in the Chicago-area killings. Seven people died in September 1982 after taking Extra-Strength Tylenol capsules that had been laced with potassium cyanide, setting off a nationwide product recall and an investigation that has remained unresolved for more than four decades.
Betkouski was found dead Dec. 4, 1982, inside Sacred Heart Catholic Church in Boise. For decades, investigators knew him only as the “Unknown Wanderer.” He had no identification that revealed his real name, and early attempts to identify him through fingerprints and other investigative methods were unsuccessful. Among his possessions were nearly 30 keys, $1,900 in cash and a typed note signed with a name investigators later determined was an alias.
The case received national attention when it was featured on “Unsolved Mysteries” in 1990, but the man’s identity remained unknown. Ada County Cold Case Detective Tim Cooper returned to the investigation years later and compared the case against more than 17,000 missing-person records. Investigators said Betkouski had never been reported missing, limiting the usefulness of one of the most common tools for identifying an unknown person.
A break came from another look at the keys recovered with the body. Investigators traced markings on one key to Jacksonville, Florida, and an engraving led them to Mills Court, a street in the city. Property records eventually pointed investigators toward Betkouski’s family. A surviving brother provided a DNA sample, which investigators compared with DNA associated with evidence from the Boise case. The familial match allowed authorities to identify the Unknown Wanderer as Betkouski.
Investigators then began reconstructing Betkouski’s life and movements. They determined that he was a trained chemist who had lived and worked in several states, including Florida, California and New Mexico. According to investigators, former colleagues recalled statements by Betkouski involving cyanide and the possibility of introducing poison into over-the-counter capsules. Those accounts, combined with the unusual circumstances of his own cyanide death shortly after the Chicago poisonings, drew the attention of detectives reviewing the cold case.
Other findings have raised questions without establishing that Betkouski committed the Tylenol killings. Investigators found evidence that he had visited Chicago before the murders, including photographs showing him there in 1981, but authorities have not established that he was in the Chicago area when the poisoned capsules killed seven people in late September 1982. Investigators also recovered cyanide connected to Betkouski, but authorities said it was a different form from the potassium cyanide used in the Tylenol poisonings.
Ada County investigators have also examined other poisoning deaths that had been discussed in connection with the unidentified man. Authorities said Betkouski has been ruled out in some other homicide cases previously associated with the Unknown Wanderer. The sheriff’s office has emphasized that its investigation does not establish Betkouski as the person responsible for the Tylenol murders and that determining whether he should be considered a suspect in those killings falls to the agencies with jurisdiction over the Illinois cases.
The Tylenol murders began Sept. 29, 1982, when people in the Chicago area began dying after taking capsules contaminated with cyanide. Seven deaths were eventually linked to the poisonings. The case triggered a nationwide response, including the removal of Tylenol capsules from store shelves, and helped drive major changes in tamper-resistant packaging for consumer medicines. Despite an extensive investigation and scrutiny of several people over the years, no one has been convicted of carrying out the killings.
Idaho investigators have shared information from the Betkouski investigation with authorities involved in the Illinois cases. They are particularly interested in establishing his whereabouts and activities during the period before he appeared in Boise. That gap remains important because investigators have not produced direct evidence placing him at the Chicago-area locations where the poisoned medicine was distributed when the murders occurred.
The identification therefore resolves one mystery but not the larger one surrounding the Tylenol deaths. Authorities now know the name of the man who died in the Boise church, but whether information about Betkouski will advance the decades-old Chicago investigation remains unresolved. Investigators continue to seek information about his travels, contacts and activities during the final months of 1982.
Author note: Last updated September 24, 2026.