Mark Pavelich, a member of the "Miracle on Ice" 1980 Olympic hockey team, was found dead at a treatment facility in Minnesota, USA Hockey confirmed on Friday.

The cause of death was not immediately known. Pavelich was 63.

"We are saddened to hear about the passing of 1980 Olympic gold medalist Mark Pavelich," USA Hockey tweeted. "We extend our deepest condolences to Mark's family & friends. Forever a part of hockey history."

The (Minneapolis) Star Tribune first reported details about Pavelich's death. According to the newspaper, police were called to Pavelich's residence at the facility at about 8:30 a.m. local time on Thursday where he was found dead. He was last seen on Wednesday at about 8 p.m. at the facility, where he was receiving mental health treatment.

Pavelich was living at the facility after a court ruled he was unfit to stand trial for an August 2019 assault on his neighbor. Pavelich was charged with four felony counts for the assault, which left the victim with several broken bones.

The judge said that Pavelich "lacks the ability to rationally consult with counsel, is incapable of understanding the proceedings, and is incapable of participating in the defense due to mental illness or deficiency." Pavelich assaulted the neighbor with a metal rod.

Pavelich's sister, Jean Gevik, told the Star Tribune in 2019 that the family believed Pavelich might be suffering from chronic traumatic encephalopathy (CTE).

"Mark is the most kind and gentle person you'd ever know," Gevik told the newspaper. "This is a totally different guy." Gevik said that her brother had a history of concussions in the NHL.

Pavelich, a 5-foot-8 center, was an All-American at the University of Minnesota Duluth. He assisted on Mike Eruzione's game-winning goal that took down the heavily favored Soviet Union in the 1980 Olympics. Pavelich played in the NHL from 1981 to 1987 and in the 1991-92 season. He spent five seasons with the New York Rangers and also played for the San Jose Sharks and Minnesota North Stars.

"The New York Rangers are saddened to learn of the passing of Mark Pavelich," the Rangers said in a statement. "His determination, passion, and dazzling playmaking ability earned him the adoration of Rangers fans during his five-year tenure in New York. Mark helped inspire a nation through the integral role he played on the 'Miracle on Ice' team in the 1980 Winter Olympics. Our thoughts are with Mark's loved ones during this difficult time."