LEWIS COUNTY, Wash. -- Dennis Hadaller made a promise to his mother at her funeral in 1985.
"I put my hand on her casket and said I'll do anything I can to help solve this terrible murder," said Hadaller.
Nearly 28 years later, he helped fulfill that promise.
Ricky Riffe will spend the rest of his life in prison for the 1985 murders of Hadaller's parents, Minnie and Ed Maurin.
Lewis County Judge Richard Brosey sentenced Riffe to just under 103 years.
"Justice has been served," said Hadaller.
Hadaller hired a private investigator to help Lewis County detectives look into the killings.
The Maurins, who were in their 80s, were kidnapped and forced to withdraw $8,500 cash out of their bank account in December of 1985. Their bodies were found a week later, on Christmas Eve. They had been shot in the back and left in the woods.
Riffe and his brother John were always considered suspects, but investigators said until last year, witnesses feared testifying against them.
John Riffe died two weeks before Lewis County detectives went to Alaska to arrest the brothers in July of 2012.