CUSTER COUNTY, Idaho — A cold case trial was suspended after concerns about the mental and physical health of the 86-year-old defendant, a judge ruled.

Magistrate Judge James Barrett found Walter Mason lacked the capacity to proceed trial or make informed decisions about treatment, the Post Register reported Thursday.

“The Court finds (Walter James Mason) lacks fitness to proceed in that the defendant is incapable of assisting in the defense of this case,” Barrett said in a court decision issued Nov. 18.

The decision delays a case that was on hold for about 40 years, officials said.

Custer County prosecutors charged Mason with murder in September 1980 days after authorities suspect he fatally shot Daniel Mason Woolley over a relationship dispute, court officials said.

RELATED: Man arrested in central Texas in connection to 1980 Custer County cold case murder

Mason was arrested last month after he was found in Eastland County, Texas.

His attorney David Cannon didn’t return a request for comment.

Willie and Brenda Ezzell lived across the street from Mason for more than two decades in Texas, but did not interact with their former neighbor often, Willie Ezzell said.

“He’s in real poor health,” Brenda Ezzell told the Post Register in October. “He can barely get around, and his house was a complete wreck.”

Mason is in custody at the Idaho Department of Health and Welfare for up to 90 days, officials said.

Court records did not state the specific health concerns that led to the ruling.

Watch more crime:

See the latest Treasure Valley crime news in our YouTube playlist: