Herschel Walker has always been something of a puzzle. As difficult as the star running back was to bring down on the field, it was harder, still, to figure out what made him tick.
"I told somebody once, 'You don't want the Herschel that plays football ... babysitting your child," Walker told ABC News correspondent Bob Woodruff. "When I am competing, I am a totally different person.'"
He means it literally.
For the first time, the 46-year-old former professional football player reveals in a book published this week, "Breaking Free," that he has a rare and controversial mental illness called dissociative identity disorder — or D.I.D. — formerly known as multiple personality disorder.
"I had it the whole time, I just didn't know what it was," Walker said.
The athlete who played 15 seasons of professional football in the NFL and USFL and pushed a bobsled for the 1992 U.S. Olympic team in Albertville, France; the family man who married his college sweetheart; the man who once danced with the Fort Worth Ballet; the business man — Walker says none of those guys were him. Not really. Those were his "alters," he says -- alternate personalities.
Walker's family, former teammates and fans reacted to the revelation with shock.
"I know him better than anybody 'cause I raised him," Walker's father, Willis Walker Sr. told the Atlanta Journal-Constitution in January. "This is my first knowing about that."
The disorder usually has its roots in childhood trauma.
"I was a fat little kid with a speech impediment," Walker told Woodruff. "I used to get beat up, not just picked on."
Walker's therapist Jerry Mungadze, said he met Walker's alternate personalities, or alters, in therapy. "They will come out and say, I am so-and-so. I'm here to tell you Herschel is not doing too good ... When he finishes, it would just disappear back in him, and Herschel comes out."
Walker and Mungadze believe the disorder actually helped Walker — who started for a number of NFL teams, including the Minnesota Vikings and the Dallas Cowboys — succeed on the gridiron.
Mungadze offered a theory about the subconscious logic in Walker's head. "Since people are laughing at you, we're going to make you so strong, so fast, so talented, that you're going to be above everyone. And that is what went into building this super athlete."
But shortly after retiring from football, Walker descended into mental mayhem. At one point, Walker says he sat alone at his kitchen table and played Russian roulette with a loaded pistol. Walker told Woodruff, "To challenge death like I was doing, you start saying, there's a problem here."
Walker's diagnosis answered a lot of questions for Walker's ex-wife Cindy Grossman, who was married to Walker for 16 years before she knew about the illness.
"Well, now it makes perfect sense, because each personality has a different interest. This one has an interest in ballet, this one has an interest in the Marines, this one had an interest [in the] FBI, this one had an interest in sports," she said.
Grossman recognized different sides of her husband, even different voices. "It's hard to explain, but even his physical countenance would change. ... There was also a very sweet, lovable [personality]. That's the one he told me I married. He told me I didn't marry Herschel."
But there were darker moments.