Jefferson County Sheriff Craig Doolittle tells NBC Montana the death of Jim Ryan is being classified as a suicide.
Ryan's body was discovered near Homestake Pass in June.
He was reported missing in February, the same day he was supposed to meet representatives of the Helena Sheet Metals Workers Union about $175,000 that went missing.
The Lewis and Clark County Sheriff's Office later confirmed that Ryan was under investigation for possible embezzlement.
Police traced Ryan's car to the Homestake Pass area, but initial searches of the area turned up no sign.
Doolittle says a toxicology report showed Ryan died from multiple drug toxicity. Investigators believe it was intentional.