SACRAMENTO, Calif. — Investigators hunting down the so-called Golden State Killer used information from genetic websites last year that led to the wrong man, court records obtained Friday by The Associated Press showed.

An Oregon police officer working at the request of California investigators persuaded a judge to order a 73-year-old man in a nursing home to provide a DNA sample.

It’s not clear if officers collected the sample and ran further tests, but it was not the man arrested this week outside Sacramento in one of the state’s most notorious string of serial rapes and killings.

The case of mistaken identity was discovered as authorities hailed a novel use of DNA technology that led this week to the arrest of former police officer Joseph DeAngelo at his house outside Sacramento on murder charges. He’s suspected of being the sadistic attacker who killed 13 people and raped nearly 50 women during the 1970s and `80s.

Handcuffed to a wheelchair in orange jail scrubs, DeAngelo made his first court appearance Friday. The 72-year-old looked dazed and spoke in a faint voice to acknowledge he was represented by a public defender. He did not enter a plea.

He has been charged with eight counts of murder, and additional charges are expected, authorities said.

“We have the law to suggest that he is innocent until he’s proven guilty and that’s what I’m going to ask everyone to remember,” DeAngelo’s public defender Diane Howard said outside court. “I feel like he’s been tried in the press already.”

Investigators were able to make the arrest this week after matching crime-scene DNA with genetic material stored in an online database by a distant relative. They relied on a different website than they had in the Oregon search, and they did not seek a warrant for DeAngelo’s DNA.