The New Orleans Advocate recently published a shocking story that details the very real threats to privacy and civil liberties posed by law enforcement access to private genetic databases and familial DNA searching.

In 1996, a young woman named Angie Dodge was murdered in her apartment in a small town in Idaho. Although the police collected DNA from semen left at the crime scene, they haven’t been able to match the DNA to existing profiles in any criminal database, and the murder has never been solved.

Fast forward to 2014. The Idaho police sent the semen sample to a private lab to extract a DNA profile that included YSTR and mtDNA—the two genetic markers used to determine patrilineal and matrilineal relationships (it’s unclear why they reopened the case after nearly 20 years). These markers would allow investigators to search some existing databases to try to find a match between the sample and genetic relatives.

The cops chose to use a lab linked to a private collection of genetic genealogical data called the Sorenson Database (now owned by Ancestry.com), which claims it’s “the foremost collection of genetic genealogy data in the world.” The reason the Sorenson Database can make such an audacious claim is because it has obtained its more than 100,000 DNA samples and documented multi-generational family histories from “volunteers in more than 100 countries around the world.” Some of these volunteers were encouraged by the Mormon Church—well-known for its interest in genealogy—to provide their genetic material to the database. Sorenson promised volunteers their genetic data would only be used for “genealogical services, including the determination of family migration patterns and geographic origins” and would not be shared outside Sorenson. Its consent form states:

The only individuals who will have access to the codes and genealogy information will be the principal investigator and the others specifically authorized by the Principal Investigator, including the SMGF research staff.

Despite this promise, Sorenson's vast collection of data, like data in other public DNA databases, is available online and may be searched by anyone with "DNA results obtained from a commercial lab." This means, without a warrant or court order, investigators were able to run the crime scene DNA against Sorenson’s private genealogical DNA data. The search turned up 41 potential familial matches, one of which matched on 34 out of 35 alleles—a very close match that would generally indicate a close familial relationship. The cops then asked Ancestry.com, not only for the “protected” name associated with that profile, but also for all “all information including full names, date of births, date and other information pertaining to the original donor to the Sorenson Molecular Genealogy project.” Ancestry.com offered to disclose this information in response to a simple subpoena, but the police got a search warrant instead.

This is when the case starts to sound like something out of the TV show “CSI.” Ancestry.com linked the crime scene DNA to DNA from a man born in 1952. That man didn’t fit the age profile of the murderer, so the investigators used the genealogical information to trace his male descendant line and find his son, Michael Usry Jr., born in 1979. Then the cops searched Usry’s Facebook page and found he had some Facebook friends who lived somewhat near Idaho Falls. And then through Google searches, the police learned Usry was a filmmaker who had been involved in making a few short films that had homicide or killings in the story line. (The cop noted in a warrant affidavit “these short films have won awards in several film festivals.”) Based on this completely circumstantial evidence, the Idaho investigators got a warrant to collect a swab of Usry’s DNA.

They called up Usry, told him they were investigating a hit-and-run, and asked him to meet with them. Usry thought he “had nothing to hide” and agreed to the meeting. They took him to an interrogation room, questioned him without a lawyer present, and eventually collected a DNA sample. Then Usry sat on pins & needles for a month waiting for the results.

When the results came in, it turned out Usry’s DNA didn’t match the crime scene sample—despite the close familial markers and other circumstantial evidence, he wasn’t the murderer.

Usry was lucky. The forensic crime scene DNA sample came from semen and likely was single source (meaning it contained DNA from only one person). This means that it was relatively easy for the cops to compare Usry’s DNA against the forensic sample and determine conclusively the two didn’t match. In many cases today, however, forensic samples come instead from “touch” DNA—miniscule samples of DNA deposited on physical surfaces that people have touched. Touch DNA is less reliable and harder to match both because it may not include enough DNA for meaningful interpretation and because it often contains DNA from multiple persons—some of whom may have had no connection to the crime at all. With touch DNA, lab analysts may see a match where none exists. Just this year in San Francisco, the San Francisco Chronicle revealed a crime lab analyst had been making assumptions about poor-quality, incomplete genetic evidence and testified at trial that one of the profiles she generated matched the defendant, which was false. This analyst’s misconduct could affect as many as 1,400 cases. When touch DNA analysis expands to include familial markers, the risk of misidentification only increases.

This risk will increase further as state and local law enforcement agencies begin to use Rapid DNA analyzers—portable machines that can process DNA in less than an hour. These machines will make it much easier for police to collect and analyze DNA on their own outside a lab. Currently, because forensic DNA analysis in a lab takes so long, we generally see its use limited to high-level felonies like rape and murder. However, Rapid DNA manufacturers are now encouraging local police agencies to analyze DNA found at the scene of low-level property crimes. This means much more DNA will be collected and stored, often in under-regulated local DNA databases. And, because most of the forensic DNA found at property crime scenes is likely to be touch DNA—this only increases the risk that people will be implicated in crimes they didn’t commit.

Most states and the federal government don’t yet extract YSTR and mtDNA and so don’t store it in their criminal DNA databases. For this reason, even if one of your relatives already has DNA in a criminal database, the risk you would be implicated through familial searching is low. But if the cops can access private databases—especially private databases like Ancestry.com and 23 and Me that collect matrilineal and patrilineal markers—everyone’s risk increases.

This case highlights the extreme threats posed to privacy and civil liberties by familial DNA searches and by private, unregulated DNA databases. People should be able to learn about their ancestors and relatives and about possible risks for genetic diseases without fear that their data will be shared with the cops without their consent. However, Usry’s case shows that we can’t count on private companies’ internal policies to keep our private data safe, and we should think twice before sharing our genetic information with a third party.