"This was a murder-suicide spree that lasted over, I believe, a three-day weekend," Bailes said. "I don't think that 'roid rage,' which is believed to be a snap judgment ... in emotions or actions, I don't think this is what explains Chris's behavior."
Desperate for more answers and disgusted with the media for painting a picture of his son as a juiced-up murderer, Benoit decided to give his son's brain to scientists for further study.
When researchers examined the wrestler's brain tissue under a microscope, they said they found evidence of years of repeated blows to the head, indicating severe brain damage.
"Chris's damage was extensive. It was replete across multiple areas of the brain," Bailes said. "It remains one the worst we have seen."
Bailes and neuro-pathologist Dr. Bennet Omalu had studied other athletes' brains before Benoit. One was former Pittsburgh Steelers Hall-of-Famer Mike Webster, who had dissolved into a shell of his former self after retiring at age 38.
After finding severe damage in Webster's brain, Omalu called the new condition "Chronic Traumatic Encephalopathy" (CTE), caused by repeated blows to the head. He plans to rename the condition, "Mike Webster's Disease."
Bailes stated that both Webster and Benoit's brains were similarly damaged, but cautioned that brain scans alone can't prove Benoit's battered brain drove him to murder.
"I think even if you had a great psychiatric input on this case that you couldn't come up with why human behavior can become so severe," he said.
Benoit was believed to have been prone to insomnia, mood swings, depression and alcohol abuse. All of these behaviors can be symptoms, doctors say, of brain damage.
After learning their findings, Mike Benoit believes that hardcore wrestling caused his son to go from being a loving, caring person to an evil one.
"I think if Chris Benoit had been anything other than a professional wrestler ... he would still be alive," he said.
The WWE vehemently disagreed with this position and questioned the scientific findings on Benoit.
In a statement to ABC News, they said Benoit's claim that head trauma could be the "cause of his son's aberrant, criminal behavior ... is impossible." Click here to read the full statement.
WWE argued if he was suffering from extensive brain damage, he would not have been able to function as a pro-wrestler, "much less commit a methodical murder-suicide over a 48-hour period."
Mike Benoit continues to defend his belief about his son's death and denies that he's using brain damage as an excuse for the murder-suicide.
"I would like people to have an understanding that the tragedy that took place in 2007 happened because of his career choice," he said.
Watch the full story tonight on "Secrets of Your Mind" at 10 p.m. ET.