— Covered in blood and still holding a large knife that police say he’d used just minutes before to nearly decapitate his brother’s roommate, Isaiah Zoar Marin dialed 911.

“I murdered someone,” Marin told the operator.

Moments later Wednesday afternoon, police say they found Marin running west near a car dealership on State Highway 51, still carrying the weapon. When they asked Marin where he was coming from, authorities say Marin directed them to a nearby apartment where they found the body of Jacob Andrew Crockett, 19, of Stillwater.

On Thursday, Marin, 21, was charged with first-degree murder. Police say Marin confessed to killing Crockett. The men had been classmates at Stillwater High School, the school’s principal said.