Former Grand Valley State University (GVSU) star quarterback Cullen Finnerty's autopsy revealed he had died from pneumonia the night he went missing in May, the New York Times reported.

The autopsy was released Thursday by the Lake County Sheriff's Department and said the pneumonia, combined with oxycodone toxicity and the degenerative brain disease chronic traumatic encephalopathy (CTE), caused his death.

Finnerty had been found dead in May alone in the woods in Michigan without an explanation for how he died. The autopsy findings gave a definitive answer.

He had gone fishing alone on May 26 in Baldwin, Mich. and went missing. He was found two days later face down in a clearing about half a mile from where he docked the boat.

"A likely sequence of events on the night of death includes anxiety, disorientation and paranoia from being alone in the woods," the report said. "Those emotions could have been exacerbated by an elevated oxycodone level combined with C.T.E."

Finnerty had been taking the oxycodone for back pain. At some point during that night, he became incapacitated and vomited. Inhaling the vomit caused the pneumonia.

The brain disease and oxycodone likely caused him to become paranoid, the Associated Press reported, as he had called two family members that night and seemed disoriented and suspected someone was following him.

Tests on his brain, performed at the Center for the Study of Traumatic Encephalopathy at Boston University, confirmed he had stage 2 (of four stages) CTE.

Finnerty and his GVSU football team won were an unstoppable force in NCAA Division II football. He won three national championships and was though to have more wins than any other quarterback in college football history.

He went on to play in the NFL for the Baltimore Ravens and Denver Broncos, as well as for teams overseas.

He is survived by his wife and two children.