The Collin County (Texas) Medical Examiner's Office has determined former Cowboys running back Marion Barber's death was caused by heat stroke, the Frisco Police Department confirmed to NFL.com on Monday.
The office has officially ruled Barber's death as accidental.
Barber, 38, was found dead inside an apartment on June 1 following a welfare check conducted by the Frisco Police Department. The cause of death was unknown at the time his body was found.
"We are heartbroken by the tragic death of Marion Barber III," the Cowboys said in a statement last month. "Marion was an old-school, hard-nosed football player who ran with the will to win every down. He had a passion for the game and love for his coaches and teammates. Our hearts go out to Marion's family and friends during this difficult time."
From 2005 to 2011, Barber made every one of his seven seasons in the NFL count thanks to his tenacious running style. A fourth-round draft pick by the Cowboys out of the University of Minnesota, Barber quickly became a fan favorite with his nose for the end zone and an uncanny ability to shed tacklers. Barber earned Pro Bowl honors in 2007 after gaining 975 yards and 10 touchdowns on the ground and 44 receptions for 282 yards and two more scores through the air.
Following the 2010 season, Barber signed with the Bears and spent his final season in Chicago before announcing his retirement in March 2012.
Barber totaled 4,780 rushing yards, 1,330 receiving yards and 59 touchdowns during his NFL career.