Medical examiners in Collin County, Texas, have determined former Dallas Cowboys running back Marion Barber III died of heat stroke, an autopsy report shows, according to USA Today.

Barber, 38, was found unresponsive by Frisco, Texas, police on June 1 who were making a welfare call to his apartment. A neighbor had reported that water was leaking from his apartment and officers were called. The apartment’s staff could not contact Barber and his door was locked.

The autopsy report says that when officers went into the unit, Barber’s bathtub faucet was running and the apartment’s thermostat was set to 91 degrees with the heat set in the “on” position. Exercise equipment was also found in the apartment. The report noted that Barber was “known to exercise in sauna-like conditions.”

Some athletes take up training in saunas because it is believed that it raises the heart rate and intensifies their workouts, leading to several health and fitness benefits. But doctors say there are risks to working out in a sauna for those who have heart conditions, may have a chronic illness or are pregnant.

RELATED: Marion Barber, Former Dallas Cowboys Running Back, Found Dead In Apartment

Police said that Barber’s family had not heard from him for nearly a week before his body was found. But they did say that he had a history of medical problems and mental health issues, USA Today reports.

Barber, drafted from the University of Minnesota in 2005, played seven seasons in the NFL, including six for the Cowboys (2005-2011). During his career, he compiled 4,780 rushing yards and 53 touchdowns.

He played his final campaign for the Chicago Bears in 2011 and retired prior to the start of the 2012 season.

"We are heartbroken by the tragic death of Marion Barber III," the Cowboys said in a Twitter post after Barber’s passing, calling him an “old-school, hard-nosed football player who ran with the will to win on every down."