Court records obtained by The Associated Press show that in March 2017 investigators in Clackamas County, Oregon, convinced a judge to order the 73-year-old man to provide a DNA sample.
VIDEO: CoCo County Investigator Paul Holes is '100 percent sure' they have 'Golden State Killer'
The documents said they used a genetic profile based off DNA from crime scenes linked to the serial killer and compared it to information from genealogical websites. They created a family tree and used public records to identify the Oregon man.
Investigators also cited a rare genetic marker, which the Oregon man shared with the killer, to get the judge to issue the order.
VIDEO: Forensic psychologist examines mind of accused 'Golden State Killer'
Earlier this week, police say they arrested the right man for a dozen killings and 50 rapes from 1976 to 1986. He is Joseph DeAngelo, a 72-year-old former police officer who lived in the Sacramento area.
FROM THE ARCHIVE: 'Golden State Killer' investigation moves to Walnut Creek in 1978
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