Former Broncos receiver Demaryius Thomas died due to “complications of seizure disorder,” according to the Fulton County (Ga.) Medical Examiner’s result, which was obtained by The Denver Post on Friday.

Thomas, 33, died last Dec. 9 at his home in Georgia.

Last month, his family announced that an exam of Thomas’ brain by Boston University researchers diagnosed him with stage 2 of chronic traumatic encephalopathy (CTE).

In her report, Karen Sullivan of the Fulton County Medical Examiners cited the Boston University report and said: “It is unknown whether Mr. Thomas’ seizure disorder is a result of natural causes or a sequela of head impacts incurred during his career as a professional football player and the reviewed medical records do not include an etiology for Mr. Thomas’ seizures.”

Sullivan wrote “different physiologic events may contribute to sudden death in individuals with a seizure disorder,” and an abnormal heart rate during or after a seizure may lead to death.

At the time of his death, Thomas weighed 231 pounds. No other injuries, such as facial fractures, were discovered during the autopsy.