Daniel Kerrigan, a welder, worked three jobs at a time to support his daughter's career on the ice.
"What's money?" he asked in 1992. "I've been broke all my life. I'll be broke the rest of my life. It doesn't matter."
The murky circumstances of his death have stunned many.
Even Tonya Harding, Nancy Kerrigan's one-time chief rival who was banned from figure skating for her role in an attack on Kerrigan before the 1994 Olympics, released a statement after the attack.
"Tonya feels very sad for Nancy and her family and extends her deepest sympathy and condolences to them," the statement read. "Tonya's beloved dad, Al Harding, passed away this past April, so she understands the grief Nancy and her family are feeling at this difficult time."
Local and state police were called to the house in Stoneham, Mass., at 1:30 a.m., where they found Daniel Kerrigan, 70, "in need of medical attention." He was taken to Winchester Hospital where he was pronounced dead, according to a statement from Middlesex County District Attorney Gerry Leone.
"He [Mark Kerrigan] stated that he wanted to use the phone, and his father would not let him,'' according to a Stoneham police report filed in court. "He said that he struggled with his father and put his hands around his father's neck, and his father fell to the floor. He said that his father was faking it.''
According to the report, Mark Kerrigan appeared intoxicated -- smelling of alcohol and seen trying to conceal a bottle of whiskey -- and was belligerent as police officers tried to help his father. Police said in the report they found blood near where Kerrigan was found and pictures knocked off the walls.
"Officer Mahone grabbed his [Mark's] arm when Kerrigan became belligerent and combative. We were finally able to handcuff him. While handcuffed, I used pepper spray to help control the situation," reads the police report.
Reached by phone, Brenda Kerrigan, Nancy's mother, told ABCNews.com that her husband died from a heart attack.
"I'll tell you something, it's a shock. It was a massive heart attack. That's how he died, that's it," said Brenda Kerrigan.
Nancy Kerrigan won a silver medal at the 1994 Winter Olympics in Lillehammer, Norway. She became the center of a media firestorm when, a month before the Games, she was attacked by Tonya Harding's ex-husband.
Kerrigan retired from active competition after the 1994 Olympics. She has appeared in occasional skating exhibitions, and had a small part in the 2007 Will Ferrell film "Blades of Glory."
In 1995, Kerrigan married her agent, Jerry Solomon. They live a few miles away from her parents' home in Lynnfield, Mass. Calls from ABCNews.com to Solomon requesting comment were not immediately returned.
Mark Kerrigan has a lengthy police record of petty crimes, including marijuana possession and a history of domestic troubles with his ex-wife and parents.
In a 2005 domestic-abuse incident with wife Tammy Kerrigan, police found Mark drunk and throwing things in the yard, according to a police report obtained by the New York Daily News.
Police found Mark brandishing two hunting knives and yelling, "F**king shoot me, I want to die, kill me please!"
As recently as Jan. 8, a lawyer for Mark Kerrigan filed documents in an ongoing appeal of charges of assault with a deadly weapon and malicious destruction of property dating from 2006.