Ada County investigators identified the man found dead under a Boise church pew in 1982 as Dr. Mathew Francis Betkouski, saying he died by cyanide suicide and left a note and $1,900.
A property deed tied to a key found on his body and a DNA swab from his brother solved the case after more than 40 years, despite no fingerprint match with local or FBI files.
Detectives said Betkouski appeared to have concealed his identity — including dye in his hair — and came from a prominent Los Angeles-area family with civic and government ties.
The identification revived scrutiny of a possible link to the 1982 Chicago Tylenol murders because Betkouski had homemade sodium cyanide, a 1970s Chicago map and had discussed poison and pill tampering.
Police said he has never been named a suspect and cannot be placed in Chicago during late September 1982; the cyanide found with him also differed from the potassium cyanide used in the seven Tylenol killings.