Authorities in Idaho announced Wednesday that they have identified a man found dead in 1982 as Dr. Mathew Francis Betkouski, whom they consider a possible suspect in the 1982 Chicago-area Tylenol murders. Betkouski died by suicide from cyanide poisoning inside a Boise church in December 1982 and was buried anonymously until DNA testing and an engraved key helped confirm his identity.
The identification follows a cold case investigation reopened in 2019 by Detective Tim Cooper of the Ada County Sheriff’s Office. Detectives noted a possible link to the 1982 killings of seven people in the Chicago area, where victims consumed Tylenol capsules laced with cyanide. While Betkouski never lived in Illinois, he was documented visiting the Chicago area in December 1981.
During the investigation, authorities discovered homemade cyanide in Betkouski's former belongings, though Detective Cooper noted it was a different compound than the one used in the Chicago murders. Former acquaintances reported that Betkouski, who had a history of mental health treatment and had worked in drugstores, was fascinated by the concept of a "perfect crime." Maps of Chicago were also found among items recovered after his brother’s death in 2021.
The development involves law enforcement agencies including the Ada County Sheriff’s Office in Idaho, the Chicago Police Department, the Arlington Heights Police Department, and the FBI. While Idaho officials have shared their findings, they stated they cannot formally name Betkouski as a suspect because the homicide investigation falls under the jurisdiction of Illinois authorities. The FBI stated it has reviewed numerous claims regarding the Tylenol murders over the last 44 years and remains the lead agency for releasing credible case resolutions.
The findings may prompt law enforcement in the five states where Betkouski lived—California, Texas, New Mexico, Ohio, and Florida—to review other unsolved cyanide deaths. The Chicago Police Department and Arlington Heights Police Department are reviewing the Idaho evidence to determine if there is a connection. No court dates or final resolutions have been scheduled.