"CTE possibly affected his judgment, insight and behavior, but there are other factors, including the use of medications prescribed by his doctor, that most likely contributed to the circumstances surrounding his death," the school's Center for the Study of Traumatic Encephalopathy said in a statement. "Unfortunately because of the complexity of his medications and medical status, it is impossible to determine the specific combination of factors that led to his tragic death."
What killed the record-setting Grand Valley State signal-caller, one of the winningest quarterbacks in college football history, has been a mystery for 2 ½ months.
An initial autopsy determined he had a "slightly enlarged heart and slightly cloudy lungs" but no trauma to the body. The final report from a local medical examiner includes toxicology results and the determination that he had CTE.
"The only people that will know will be Cullen and God," his father, Tim Finnerty, told The Associated Press on Thursday. "Who knows? There are all these theories."
He said his son also was taking a thyroid medicine at the time of his death, and the devastated family he left behind a wife and two children wonders if high doses could have caused him to become violently sick and confused.
During a family trip to a Lake County cottage about 65 miles north of Grand Rapids in western Michigan, Cullen Finnerty, his brother-in-law Matt Brinks and father-in-law Dan Brinks went fishing the night of May 26. The Brinks dropped off Finnerty around 8:30 p.m. and watched as he boarded a small personal inflatable pontoon boat and floated down stream.
The plan was to pick up Finnerty in about 30 minutes, but as it turned out, it was the last time they would see him alive. His body was found May 28 within a mile of where he had disappeared.
In two brief phone conversations with family members, Finnerty sounded disoriented, complained of being tailed and said he was taking off his clothes.
Finnerty's wife told investigators he had a past addiction to painkillers but had not taken any drugs since spending time in a rehabilitation center more than a year earlier. Jennifer Finnerty said it was not the first time he had a "paranoid" episode.
Instead of driving home from Detroit a year-and-a-half earlier, he took off for Grand Rapids due to fears the FBI would follow him, she said. She said her husband remained in a state of panic for four to five days.
In the autopsy report, Kent County Chief Medical Examiner Stephen Cohle said Finnerty likely became incapacitated and inhaled his vomit. Though relatives reported that Finnerty had a number of alcoholic drinks the day he died, Cohle said his blood-alcohol level was "negligible" and did not contribute to his incapacitation.
The report said it was likely Finnerty had anxiety, disorientation and paranoia from being alone in the woods while waiting for his in-laws to pick him up. Cohle said the painkiller was prescribed to Finnerty for back injuries likely sustained during his football career.
Boston University's center for study of the disease reported in December that 34 former pro football players and nine who played only college football suffered from CTE.
The NFL faces lawsuits by thousands of former players who say the league withheld information on the harmful effects of concussions. The NCAA also is being sued over its handling of head injuries.
Finnerty led Grand Valley, a Division II school, to more than 50 victories and three national titles, the last in 2006. He briefly was a member of the Baltimore Ravens and later the Denver Broncos but never took a snap in a regular season game.
"You couldn't stop that kid from playing football," said Scott Boyd, a family friend who was on the search party that found the body. He said Finnerty played to his fullest "and probably took some hits he shouldn't have."
Finnerty's father, who coached football for 35 years, said it is important to keep researching CTE and possible links to injuries not only in football, hockey, soccer and other sports. But he said life lessons and benefits of playing football are "substantial" and praised Grand Valley's response to the tragedy.
Boyd said a perfect storm of factors seemingly conspired against Finnerty, who he described as a "clean-living kid" and devout Catholic. The Brighton native lived in Howell and sold medical devices for a living.
"He was always upbeat and positive and smiling and had a warm handshake and hug for you," Boyd said.
Associated Press writer David Goodman in Detroit contributed to this report.