Anna Marie Hlavka, 20, was killed in an apartment on July 24, 1979. Authorities said Thursday her killer, Jerry McFadden, was identified using the same technology that led to an arrest last year in California in the "Golden State Killer" case.
Hlavka was sexually assaulted and strangled with an electric cord. The Portland Police Bureau said at a news conference retired detectives submitted evidence to the state crime lab in 2009 for forensic testing.
Authorities said that evidence eventually showed McFadden, who was executed in Texas for the rape and killing of an 18-year-old high school cheerleader, was Hlavka's killer.
The 51-year-old McFadden was a notorious criminal in Texas. He was sentenced to death for a daylong murder rampage in 1986 that took the life of the cheerleader as well as two other people.
Authorities said it took years of research and detective work to determine that McFadden killed Hlavka.
Portland police said an "unknown male DNA profile" was found in 2011 in evidence collected from the scene of the 1979 slaying. The profile was deemed especially good considering how much time had passed.
From 2012 to 2016, detectives collected and submitted eight subjects' DNA profiles in an attempt to identify the killer, but authorities said all came back negative.
Last May detectives researched forensic genealogy using unidentified DNA profiles from homicide scenes, the technology used to bring about the May 2018 arrest of the suspect in the "Golden State Killer" case.
Detectives contacted Parabon NanoLabs and the Oregon State Police Crime Lab and it was determined that the evidence from the Portland cold case was a good candidate for that technology.
Detectives had also collected DNA from under Hlavka's fingernails.
"I was able to compare those DNA samples to the original unknown male profile and develop that familial link, conclusively," said Dr. Janelle Moore, Oregon State crime lab forensic scientist.
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Scientists were able to map three of the four familial lines of the Portland killer and identified him as McFadden.
Detectives traveled to Texas to interview McFadden's relatives and obtain further DNA samples.
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The Associated Press contributed to this report.