DNA testing company Ancestry.com declined police access after being served a search warrant last year, according to a transparency report released last week and obtained by BuzzFeed News.

The report revealed records of the company’s insubordination when police requested access to its data for investigative genetic genealogy.

“Ancestry challenged the warrant on jurisdictional grounds and did not provide any customer data in response,” the transparency report said.

The company’s database is home to around 16 million DNA profiles, but Ancestry.com has vowed to keep its customers’ DNA and privacy information from being subject to police investigations.

One of the company’s competitors, 23andMe, which contains roughly 10 million DNA profiles, has also promised never to hand out its customers’ DNA records. Other family history companies, such as GEDmatch and FamilyTreeDNA, have opened their data for police requests in the past.

The process of investigative genetic genealogy is more reliable based on the number of samples investigators have to work with. DNA from crime scenes can be plugged in and cross-referenced with more extensive databases such as Ancestry.com to match it with partially similar DNA to find suspects based off their relatives.

This method was the primary key to finding the Golden State Killer, Joseph James DeAngelo, who was responsible for 51 rapes and 12 murders in California between 1974 and 1986. He was arrested in 2018.

Paul Holes, a retired investigator with the Contra Costa County District Attorney’s Office, led the team that worked on and solved the Golden State Killer case. He predicted that police would request permission to search GEDmatch’s database — and to obtain the genetic data held by the larger companies, according to BuzzFeed’s report.

“Of course there are going to be legal battles,” Holes said. “It would not surprise me, years down the road, if this could be a US Supreme Court issue.”