Portland police solved a 40-year-old local murder by matching crime-scene DNA to data in a public genealogy site, helping them identify a serial killer from Texas as the man who assaulted and strangled a 20-year-old woman found dead in her apartment in 1979.

The same technology led California authorities to the elusive Golden State Killer last year.

Detectives here, with the help of the state crime lab and a Virginia-based private lab they used for the first time, linked Jerry Walter McFadden of Texas to the attack on Anna Marie Hlavka. Her sister had found her body in the apartment they shared in Northwest Portland on July 24, 1979.

McFadden was executed in Texas in October 1999 for the murders of three women, including the sexual assault and strangulation of a woman in Shackelford County, Texas, just a month before the Portland killing. Investigators learned he had come to Portland on a trip with a friend in 1979 before returning home, where the former telephone cable installer became one of that region’s most notorious criminals.

The Portland case had remained dormant for decades until 2009, when retired Detective Denny Baker, volunteering his time with the bureau’s Cold Case Homicide Unit, resubmitted numerous items of evidence to the state lab for forensic testing.

Two years later, Oregon State Police forensic scientist Janelle Moore discovered an unknown male’s full DNA profile from fingernail scrapings that the initial investigators had gotten from Hlavka.

Moore said it was unusual to find a full intact DNA profile after so many years. “It was kept in a dry, dark place,’’ she said. “It was perfect.’’

But when she submitted the DNA profile from Hlavka’s fingernail scrapings into the FBI’s national crime database of offenders, no match turned up, she said.

In 2012, Portland cold case Detective Meredith Hopper picked up the case, collecting and submitting potential suspects' DNA profiles to the state lab, hoping one might help identify Hlavka’s killer.

Then last year, when police in California announced the arrest of the suspected Golden State Killer, Joseph James DeAngelo, the Portland detective became intrigued by the DNA analysis and use of genealogy databases that helped California police identify their elusive masked gunman. DeAngelo is now tied to a string of unsolved killings and rapes in California in the 1970s and ’80s.

Hopper contacted Parabon NanoLabs to determine if Hlavka’s evidence could be submitted for similar DNA testing.

The lab compared it to DNA in publicly available databases. The databases include at least 1 million profiles from anyone who shares their information from consumer DNA testing companies such as 23andMe and Ancestry.com to search for relatives who have submitted their DNA.

In October, the lab alerted Hopper that the profile came back to McFadden, a convicted Texas murderer and serial rapist who nicknamed himself “Animal.’’ A forensic genealogist from the lab had mapped three of the four familial lines of McFadden, according to police.

McFadden, 51, was executed by lethal injection for the rape and slaying of an 18-year-old high school cheerleader, one of three people killed during a daylong murder rampage in 1986, about 100 miles east of Dallas. At the time of his arrest in those killings, he was on parole after three rape convictions.

“If he’s such a bad guy, why wasn’t his DNA in CODIS?’’ Hooper said she wondered, referring to the FBI’s national crime database of offenders.

Hopper and partner Detective Brendan McGuire last fall traveled to Texas to learn more about McFadden and meet with his relatives. They learned that by the time the state of Texas began requiring the tracking of offenders’ DNA in 1995, McFadden already was on death row.

“Essentially, they didn’t get to him,’’ she said. “Honestly, without this technology, we never would have solved this case.’’

PPB solve 40-yr-old cold case press conference Posted by The Oregonian on Thursday, January 31, 2019

The detectives requested and obtained DNA samples from McFadden’s relatives to compare with the DNA evidence from Hlavka’s fingernails and a match was confirmed in December.

They learned McFadden had traveled to the Pacific Northwest in 1979 with a woman, who reported dropping him off in Portland but having no further contact with him.

Hopper doesn’t believe Hlavka knew McFadden. Her sister found her dead on July 24, 1979 in her Apt. 103 at 1811 N.W. Couch St. about 10 p.m., after returning home from her shift at the nearby McDonald’s restaurant. There was no sign of forced entry, but a window was open. Hopper suspects McFadden may have followed Anna Marie Hlavka home.

Her sister, Rose Ann Hlavka, and her children attended a news conference at the Police Bureau on Thursday but didn’t speak as detectives announced the closure of the case. She left before it was completed.

Retired Portland homicide Detective Kerry Taylor, who responded to Hlavka’s apartment 40 years ago, also attended.

“It’s awesome,'' Taylor said. "It’s good to see another success story, and it’s good for the community to see the hard work detectives are doing every day.’’

-- Maxine Bernstein

Email at mbernstein@oregonian.com

Follow on Twitter @maxoregonian