The Muskegon Chronicle reported that a medical examiner this week listed the manner of death for 20-year-old Amber Rose Brown of Montague and 26-year-old Douglas William Ward as undetermined.
Members of Ms. Browns family found the Grand Valley State University students dead Nov. 19 in a wooded area of Muskegon Countys White River Township, about 50 miles northwest of Grand Rapids. Carbon monoxide fumes from two charcoal grills in the vehicle were suspected in their deaths.
Investigators found the vehicles interior vents covered with duct tape, and a camera included photos of the grills with hot embers.
Police say no further investigation is planned.