The family of Chris Benoit has been searching for answers since late June, when the professional wrestler killed his wife, 7-year-old son and then himself.
At the crime scene, police found anabolic steroids prompting many to suspect that "roid rage" had accounted for Benoit's behavior, which his family found out of character for the 40-year-old.
His family now believes that new test results on Benoit's brain explain his vicious actions.
The tests, conducted by Julian Bailes of the Sports Legacy Institute, show that Benoit's brain was so severely damaged it resembled the brain of an 85-year-old Alzheimer's patient.
Bailes and his research team say that this damage was the result of a lifetime of chronic concussions and head trauma suffered while Benoit was in the wrestling ring.
Benoit's father, Michael Benoit, is speaking out in order to warn other athletes, both professional and student.
Dementia Caused by Multiple Concussions, Doctor Says
After hearing the news that his son had murdered his 7-year-old son, Daniel, and wife Nancy and then killed himself, Michael Benoit struggled to understand how it could have happened.
Michael says Benoit was a "kind and gentle" man who volunteered with the Make-A-Wish Foundation and visited U.S. troops overseas in Iraq.
"First we needed an understanding. The person that did this is not the man we know and love," Michael said today on "Good Morning America."
After the suicide and murders, Michael was contacted by a former wrestler, who suggested he investigate whether years of trauma to Benoit's brain could have contributed to his actions.
"I was grasping for anything," Michael told ABC News' Bob Woodruff. "The world was very black. I mean, we didn't even know how to deal with this."
So Michael turned over part of his son's brain to Bailes, the head of neurosurgery at West Virginia University and former Pittsburgh Steelers team physician.
Bailes and his research team had also analyzed the brains of former NFL players such as Andre Waters and Terry Long, who both committed suicide. Bailes and his colleagues theorize that repeated concussions can lead to dementia, which can contribute to severe behavioral problems.
"There is a constant theme in the failure of their personal lives, their business lives, depression and then ultimately suicide," Bailes said.
Similar Brain Damage Found in Other Athletes
Bailes and his research team took samples from Benoit's brain postmortem and compared these microscopic brain scans to those of a healthy brain.
They found that Benoit's brain showed an advanced form of dementia that appears on the brain scan as brown clumps or tangles. These brown spots are actually dead brain cells, killed off as a result of head trauma, said Bailes.
In Benoit's case, the damage was found in every section of the brain — all four lobes and deep into the brain stem.
"It was extensive throughout Chris' brain," Bailes said. "This is something you should never see in a 40-year-old."
The damage is proof, Bailes said, that Benoit suffered multiple, probably chronic, concussions over the course of many years.
Benoit, in fact, told friends he had suffered "more concussions than he could count."
Benoit's brain showed the same kind of damage Bailes and his team found in four retired NFL players who also suffered multiple concussions and later sank into deep depressions and harmed themselves or others.
Perhaps most disturbing, a person doesn't need to have sustained dozens of concussions to see problems later in life.
"Our research shows that three concussions may be the threshold for lasting damage," Bailes said.
This kind of brain damage isn't new to athletes, but doctors and researchers are starting to understand it better. As far back as the 1920s, career boxers were diagnosed with "punch drunk syndrome," which is now known as chronic traumatic encephalopathy.
Bailes said that while he can't be certain that the brain damage caused Benoit's actions, he believes it is the leading cause.
"We think these changes are not due to steroids," Bailes said. "That has never really been studied, but it's never been in the medical literature or any research that shows steroids do this to the brain. These changes [in the brain] were found in the 1920s before steroids were even invented."
For Michael Benoit and the family, these test results provide a small amount of comfort.
"Bascially, once the findings came out and I had the opportunity to talk to the doctors, we certainly had an understanding of what could have contributed to the tragedy that took place that day," Michael said.
The message Michael would like Benoit's surviving children to take away is that "their dad loved [them] dearly and what happened wasn't his fault."