Bears legend Dick Butkus died at 80 in October after suffering a stroke, according to the death certificate obtained by TMZ.
The certificate lists a “cerebrovascular accident” as the cause of death, which is more commonly known as a stroke.
The death certificate also lists secondary causes, which included an irregular heartbeat and thick/hardened arteries.
Butkus had been dealing with an irregular heartbeat in the weeks before his death and had issues with his arteries for years, according to TMZ.
The death certificate also mentioned Butkus’ coronary bypass surgery that he had done in 2001.
Butkus was pronounced dead at the scene after paramedics were called to his Malibu home on Oct. 5 at 12:51 p.m., according to the outlet.
The Bears and Butkus’ family announced his death in a statement later that day.
The Commanders, who hosted the Bears on “Thursday Night Football” that night, held a moment of silence before the game.
Butkus is widely regarded as one of the greatest linebackers in NFL history and holds the Bears’ franchise record with 27 fumble recoveries.
During the course of his career, Butkus was an eight-time Pro Bowler and five-time All-Pro but was limited to nine seasons due to a knee issue.
He spent his entire nine-year playing career with the Bears.
“Dick was the ultimate Bear, and one of the greatest players in NFL history,” Bears chairman George McCaskey said in a statement after Butkus’ death.
“He was Chicago’s son. He exuded what our great city is about and, not coincidentally, what George Halas looked for in a player: toughness, smarts, instincts, passion and leadership. He refused to accept anything less than the best from himself, or from his teammates.”
Other members of the football community weighed in after Butkus’ death, including fellow Bears great Brian Urlacher.
“I have so much respect for this man and the way he treated me. The Bears family lost a Legend today. RIP Butkus!” Urlacher wrote in a social media post.