Ronald MacDonald had entered a modified guilty plea for strangling 80-year-old Arlene Roberts in 1978. The case went cold for 30 years until the sheriff's department reopened it.
Prosecutors agreed to have MacDonald plead guilty to second degree manslaughter, then walk free on time served.
But the judge said that would be a miscarriage of justice and gave MacDonald the maximum penalty of five years in prison.
"I'm glad the judge saw the case for what it was and held him accountable," said Det. Scott Tompkins with the King County Sheriff's Department. "It was a horrible crime. I'm glad we could get some resolution to it."
Prosecutors had offered MacDonald the plea deal in part because detectives at the crime scene did not wear gloves, which could have allowed defense attorney's to question DNA evidence found at the scene. MacDonald's alleged confession to the killing was also not recorded.
MacDonald, now 51, was tracked down last year when detectives with the the King County Sheriff's Office cold case unit were reviewing Roberts' murder. MacDonald's fingerprints were in a database from multiple arrests spanning more than two decades, and his prints came back as a match when detectives checked fingerprints collected at the murder scene.
Roberts' body was found at her home in the Lakeshore Manor Mobile Home Park at 11448 Rainier Ave South when neighbors who hadn't seen her in several days went to check on her. She was half-naked and her hands and feet were bound with nylon stockings and there was a gag in her mouth, according to investigators.
MacDonald entered an Alford plea, which is not an admission of guilt, but acknowledges that he likely would be convicted if the case went to trial.