*This story originally appeared on NBC 5 Dallas-Fort Worth.
Former Dallas Cowboys running back Marion Barber III was found dead inside his Frisco, Texas, apartment Wednesday, the team confirms.
The team told NBC 5 that Barber, 38, was found unresponsive.
In a statement released late Wednesday afternoon, the team said they were "heartbroken" by his tragic death.
Frisco police said Wednesday afternoon at 2:40, officers responded to a call about a welfare concern at an apartment in the 9400 block of Stratton Drive that was believed to be leased by Barber.
Police describe the investigation as an unattended death.
Barber, who would have turned 39 on June 10, was drafted by the Dallas Cowboys in the fourth round in 2005 and spent six seasons in North Texas where his hard-hitting, punishing style of running earned him the nickname "Marion the Barbarian."
"We are heartbroken by the tragic death of Marion Barber III. 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," the team said in its statement.
After leaving Dallas, Barber would spend a year with the Chicago Bears before retiring from professional football and returning to North Texas.
Throughout his NFL career, Barber rushed for 4,780 yards on 1,156 attempts, an average of 4.1 yards per attempt, and scored 53 touchdowns on the ground. As a receiver, he caught 179 passes for 1,330 yards with six TDs.
Barber is the older brother of former Houston Texans safety Dominique Barber and former Minnesota Golden Gophers linebacker Thomas Barber. They are the sons of former NFL player Marion Barber Jr.
Barber was also known for his humanitarian efforts, working with his foundation and giving back to his community.
Joe Krywalski, a friend of Barber's, told NBC 5 Wednesday that Barber was a great person and very generous. He said Barber was religious, played the piano and wanted to get into boxing.
Over the years Barber had several minor run-ins with the law and just last month had pleaded no contest to two 2018 charges of criminal mischief after he damaged two vehicles in separate incidents while jogging in Frisco. In 2014, when he lived in Mansfield, Barber was taken for a mental evaluation following an altercation outside a restaurant in which a car was damaged.
Billy Clark was his attorney and more. "For me, he was literally family and I'm so lost that I'm not prepared for this," Clark told NBC 5.
Clark says Barber wanted to write a book about his life, and what football and family meant to him.
He said Barber was also training to become a boxer.
"He was in tip-top shape so when I tell you I'm at a loss, I am," Clark said.
The Collin County Medical Examiner's office will determine Barber's cause of death.
NBC 5's Meredith Yeomans contributed to this report.