BOISE, Idaho — Seven people died after taking cyanide-laced Tylenol capsules in the Chicago area in September 1982.
The crime triggered a nationwide panic, changed the way medications are packaged in the United States, and launched one of the largest homicide investigations in modern history. More than four decades later, the case remains active and unsolved.
Now, an Idaho cold case has added a new suspect to the debate. The identity of a man who died by suicide inside a Boise church just two months after the poisonings was recently made public. He was Mathew Betkouski, a scientist with a Ph.D. in organic chemistry. Some investigators now believe he could be responsible for the Tylenol murders. Others strongly disagree.
WATCH LIVE | An Idaho News 6 Investigation
The Tylenol Murders: A Killer Unknown
The Crime That Changed America
The Tylenol murders began on Sept. 29, 1982, when 12-year-old Mary Kellerman died after taking Extra Strength Tylenol. Within three days, six more people were dead.
Investigators discovered someone had opened Tylenol capsules, replaced the medication inside with deadly potassium cyanide, and returned the bottles to store shelves in the Chicago area. As news spread, Americans emptied medicine cabinets, poison control centers were flooded with calls, and authorities raced to determine whether more contaminated bottles were in circulation.
Johnson & Johnson ultimately recalled 31 million bottles of Tylenol capsules nationwide. The case also changed the industry. Tamper-resistant seals, shrink wrap, and other safety measures became standard on over-the-counter medications.
But one question has never been answered: Who did it?
RELATED | 1982 Tylenol murders: What happened and why the case could have a Boise connection
The Long Search for a Killer
Over the past 44 years, investigators have examined thousands of leads and multiple theories. The most prominent suspect was James Lewis, a man convicted of sending an extortion letter demanding $1 million from Johnson & Johnson to stop the killings. Lewis served 12 years in prison for attempted extortion but was never charged with the murders.
In a 2008 interview obtained by Idaho News 6, Lewis discussed how easy it was to obtain potassium cyanide in the early 1980s. "Any high school's got it," Lewis told investigators.
Lewis died in 2023, maintaining he was not responsible for the poisonings. The case remained unsolved.
How a Boise Cold Case Reopened Old Questions
While investigators searched for the Tylenol killer, another mystery was unfolding nearly 1,700 miles away.
On Dec. 4, 1982, a man walked into Sacred Heart Catholic Church in Boise and died by suicide after ingesting cyanide. He carried no identification. For decades, investigators knew him only as the "Unknown Wanderer."
In 2019, Ada County Cold Case Detective Tim Cooper reopened the case and began reexamining evidence collected decades earlier. Among the evidence were nearly 30 keys found in the man's pockets. One key led Cooper to a property in Jacksonville, Florida. Property records pointed to a man who disappeared in 1982: Mathew Betkouski.
DNA later confirmed investigators were on the right track, and the Unknown Wanderer finally had a name.
RELATED| Who was Boise’s ‘Unknown Wanderer’? Identity revealed; possible link to 1982 Tylenol murders
Why Betkouski Became Part of the Tylenol Investigation
Identifying Betkouski allowed investigators to reconstruct parts of his life, but what they found raised new questions.
Betkouski held a Ph.D. in organic chemistry and later worked for Lockheed Martin on a NASA-related project at White Sands, New Mexico. Investigators also uncovered accounts from former coworkers who recalled unsettling conversations before the Tylenol murders.
One coworker claims to remember Betkouski discussing how someone could remove medicine from pharmacy shelves, poison it, and return it without being detected. She believed Betkouski mentioned both potassium cyanide and a common medication— "Something like Tylenol."
Investigators later found additional circumstantial connections, including cyanide among Betkouski's belongings, a Chicago-area map, and correspondence from 1981 showing an interest in traveling there the following year.
The Investigator Who Thinks Betkouski Did It
As the investigation progressed, Cooper turned to Dr. Park Dietz, a forensic psychiatrist who consulted during the original Tylenol investigation. Dietz now believes Betkouski fits the profile of the killer.
"I believe that the Unknown Wanderer is exactly the kind of person who would have committed the Tylenol murders," Dietz told Idaho News 6.
He has gone further, saying he has become convinced Betkouski was responsible, though he acknowledges the case remains circumstantial.
RELATED | Expert stands by possible Idaho link to unsolved Tylenol murders
The Biggest Problem With the Theory
Despite years of investigation, Cooper says there is no "smoking gun."
Investigators know Betkouski was alive during the period of the poisonings. They know he traveled in 1982. They know he later surfaced in Boise. What they cannot do is place him in Chicago when the Tylenol capsules were tampered with.
When asked what the strongest argument against the theory is, Cooper answered with a question: "Can you put him there the final week of September 1982?"
That missing timeline remains the biggest obstacle to linking Betkouski to the murders.
Not Everyone Believes the Boise Theory
Jeremy Margolis, a former federal prosecutor assigned to the original Tylenol task force, dismisses the theory entirely.
"No, I think it's utter nonsense," he told Idaho News 6.
Margolis argues that criminal profiles are not evidence and believes investigators are focusing on the wrong suspect. While he has repeatedly suggested he believes the original investigation identified the right suspect, he has declined to publicly name who he believes committed the murders.
Why Investigators Want More Records Released
The debate over Betkouski has renewed calls for greater transparency in the Tylenol investigation.
Idaho News 6 requested investigative records, including historical case materials and presentations referenced by sources familiar with the investigation. Most of those requests were denied. Officials cited exemptions related to an active FBI investigation.
The dispute has left competing theories difficult to independently verify. Supporters of both the Betkouski theory and alternative suspects agree on at least one thing: more records should be released to the public.
The Mystery That Remains
Identifying Mathew Betkouski solved one mystery. It did not solve the Tylenol murders.
Whether Betkouski was involved, whether another suspect was responsible, or whether crucial answers remain buried in sealed records is still unknown.
For now, Ada County investigators hope anyone with knowledge of Betkouski's whereabouts in the months before his death will send tips to ACSOtips@adacounty.id.gov.
