The 63-year-old died on March 4 at the Eagle's Healing Nest in Minnesota -- where Pavelich had been undergoing court-ordered treatment as part of a 2019 assault case.

After a thorough investigation, the Midwest Medical Examiner's Office issued a statement Monday saying Pavelich "died of asphyxia due to a plastic bag over head. The manner of death is suicide."

Pavelich -- who famously made the assist on the game-winning goal to beat the Russians in the 1980 Olympics -- had been battling mental health issues in recent years.

In fact, during his assault case -- stemming from a violent altercation with a neighbor -- the ex-hockey star was diagnosed with PTSD and multiple clinical psychologists found him to be both mentally ill and dangerous.

One psychologist testified Pavelich suffered from "mild neurocognitive disorder due to traumatic brain injury with behavioral disturbance (psychotic symptoms, aggression)" -- and suggested the condition may have been caused by repeated hits to the head.

Pavelich's family had said they believe hockey was a major contributing factor to his brain injuries.

After his stint on Team USA, Mark spent 5 seasons with the NY Rangers -- followed by brief stints with the Minnesota North Stars and San Jose Sharks.

He retired from pro hockey in 1992.

Disney famously made a movie about the "Miracle On Ice" team in 2004 -- and Pavelich was played by actor Chris Koch.