An Idaho man pleaded guilty on Friday to a cold case killing from 1992 in Washington state after he was arrested based on evidence recovered from a cigarette butt that connected him to another unsolved slaying.

Lee Miller, 54, admitted to killing 57-year-old Marilyn Hickey, a former friend of his in Bremerton, Wash., KOMO-TV reported.

Miller was arrested in January after detectives used DNA evidence that was first discovered during an investigation of the 1994 murder of 49-year-old Cheryle Barratt in Idaho.

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Hickey's body was discovered in her studio apartment in 1992. The 57-year-old was found to have been strangled and was stabbed in her chest with a pair of scissors.

Documents obtained by the Idaho Statesman said Hickey was believed to have been stabbed post-mortem.

Semen was found at the scene, but officials were unable to match it at the time. The case eventually went cold until 2006 when DNA found at the Barratt murder ended up matching unknown DNA from the Hickey slaying, according to the Statesman.

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After the Boise Police Violent Crimes Unit and detectives from the Bremerton Police Department compared notes, investigators worked to identify Miller as a suspect.

When Miller tossed out a cigarette, officials were able to take a DNA sample that ended up matching.

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Miller, who has not revealed a motive for the killings, will next head to Idaho to plead guilty for the Barratt murder. He is expected to serve time in the Idaho prison system, as part of a plea agreement, so he is near his family, KOMO reported.

Fox News' Elizabeth Llorente contributed to this report.