Eight years after he was struck in the back of the head with a baseball bat, a 26-year-old Colorado man was found lifeless in his bed last week with no obvious cause of death and no sign of foul play, Sgt. Bruce Whittich of the Longmont Police Department said.
Timothy Whalen was 18 years old when Matthew Bauer, also 18 at the time, attacked him from behind in a disagreement about a keg of beer allegedly stolen from a party near the University of Colorado at Boulder campus, according to reporting by the Associated Press.
Now local officials are trying to determine whether the events of that summer night led to his death years later. Tom Faure of the Boulder County Coroner's office said an autopsy will be expected in a couple of months.
While the cause of Whalen's death is yet to be determined,brain injury experts said it is possible that people who suffered from a traumatic brain injury can die from a related seizure years later.
In fact, research shows that those who suffer from the most severe brain injuries are statistically more likely to die early -- from a variety of causes.
"There are a couple of lines of evidence to suggest that after a particularly acute brain injury that you have shorter life expectancy, even if you survive the acute injury phase," said Dr. Steven Flanagan, director of The Rusk Institute of Rehabilitation Medicine at the New York University Langone Medical Center in New York City.
A 2007 study in the Oxford journal Brain showed 767 people admitted to a United Kingdom hospital with a traumatic brain injury were twice as likely to die as the general population in seven years following the injury.
A larger 2004 study of 2,178 patients cited in an Institute of Medicine report last year showed that people with moderate to severe traumatic brain injuries had a reduced Life expectancy by five to nine years.
However, neither study could specify whether the premature death was related to the brain injury or not.
Flanagan said doctors do know, "The longer you survive after traumatic brain injury, the more that risk of early death decreases."
Whalen survived many physical challenges in the years after his attack. Following multiple skull fractures, he spent a week in a coma and a month in the hospital, according to the Associated Press. Three lobes of his brain were affected by the attack.
Bauer pled guilty to second-degree assault in 2003 and was sentenced to seven years in prison. Even if the autopsy concludes Whalen died as a result of the bat attack, lawyers say Bauer's sentence and conviction will not change.
"It is double jeopardy because the criminal act [the beating] was already charged and he was already convicted for it," said Barry Latzer, professor of Criminal Justice at John Jay College of Criminal Justice, City University of New York in New York City.
"Under double jeopardy rules you can only get one bite at the apple," he said.
However, Latzer said double jeopardy rules only work in the criminal courts. Many families choose to bring wrongful death civil suits despite the results of criminal suits.
Whalen's family did not return messages from ABCNews.com and Bauer's brother, Art Bauer, declined to comment for the story.