The condition, which can cause erratic behavior and severe mental illness, is associated with repeated head trauma and has been found in hundreds of former NFL players in recent years.

A former agent for ex-NFL star Doug Martin released a statement on behalf of the late player's family on Monday night as details emerged in his death.

Martin was picked 31st overall in the first round of the 2012 NFL draft after a standout career at Boise State. He rushed for 1,454 yards and 11 touchdowns as a rookie to earn a Pro Bowl berth. He had 1,402 yards rushing and six TDs in 2015 when he made the Pro Bowl and was first-team All-Pro.