His death has been ruled a suicide, but the Miami-Dade police department has not made the information public yet.
Foul play was ruled out in part because no one but Duerson was seen entering his condominium for two days prior to the shooting.
According to this report from Pro Football Talk, Duerson had texted his family and asked for his brain to be studied.
In this moment of sadness for a life ended too soon, that's a positive thing and perhaps good things can come out of this tragic episode:
A friend of the family contacted Chris Nowinski, co-director of the Center for the Study of Traumatic Ecephalopathy, Thursday night. Arrangement were made for the brain to be prepped and sent to Nowinski’s program for research.
The tissue will be checked for the presence of Chronic Traumatic Encephalopathy, or CTE.
"NFL players are at high risk for CTE," Nowinski said. "It’s sad, it’s shocking that it may have been on his mind" the moments before his death."
The layman's translation of CTE, according to Wikipedia, is something you'd see in professional athletes who have been involved in very physical sports like pro football. It is:
a progressive degenerative disease found in individuals who have been subjected to multiple concussions and other forms of head injury. A variant of the condition, dementia pugilistica, is primarily associated with boxing. CTE has been most commonly found in professional athletes participating in gridiron football, ice hockey, professional wrestling and other contact sports who have experienced head trauma, resulting in characteristic degeneration of brain tissue and the accumulation of tau protein.
Football and hockey have become too violent in recent years; another former Bear of Duerson's era, Jim McMahon, has said his memory is pretty much "gone". Perhaps this can lead to some research to help prevent such injuries, or at least mitigate the effects of them, so that lives don't have to end this way.