The case began in 1883 when police looked into the disappearance and killing of truck driver, Bert Donoho, ABC reported Friday.
Investigators became suspicious of Thomas McCormick and his son Michael, who were accused of killing destitute ranch hands and hiding their bodies on their 2,800-acre ranch in Stratton, Colo.
More than two decades ago, Michael McCormick, 52, took officials to at least three bodies on the ranch and said his father was responsible for the killings, senior investigator Michael Gallagher said.
Officials said they resumed investigating the ranch after Michael McCormick was released from prison by a 2006 appeals court decision that reversed his 1987 conviction for Donoho's killing.
The court was never able to prosecute his father, who died Nov. 15, 1997, ABC said.