Ancestry.com

Ancestry.com is presented as a large consumer DNA database with a double significance in the investigation: its online resources briefly made a genetic lead look promising, while the scale of its customer database suggested a possible route to identifying unknown relatives of a perpetrator. That possibility remained constrained by the company’s refusal to work with law enforcement, which it attributed to privacy concerns and its terms of service.

Identity and Investigative Role

The book describes Ancestry.com in the context of the expanding use of genetic genealogy and consumer DNA testing. Its relevance is not that it identified the killer, but that its online resources and growing collection of profiles offered investigators and researchers a way to explore genetic relationships beyond the conventional criminal-investigation databases.

The account distinguishes between different kinds of DNA comparison. Michelle uploaded the killer’s DNA profile to a Y-STR database available online from Ancestry.com. Elsewhere, the book describes consumer testing companies as using autosomal DNA. These methods and databases should not be conflated: the first produced a tentative genealogical clue in Michelle’s search, while the discussion of autosomal testing explains the broad consumer databases that might contain relatives of an unknown offender.

The Apparent Y-STR Lead

At first glance, the result Michelle found seemed encouraging. The name at the top of the page was described as very uncommon, with only a handful of people bearing it in the United States and England, and the page showed numerous hits. The comparison estimated that the man and the DNA profile Michelle was using as the killer’s might share a most recent common ancestor eleven generations back, with a 50 percent probability of finding one at that distance.

The result did not establish that the man was the killer, or even that the apparent genealogical connection was close enough to identify him. After Michelle shared the finding with Paul Holes and other experts, she learned that tracing the man’s family back roughly 330 years would still yield only a fifty-fifty chance of finding the common ancestor. The initially striking combination of a rare name and multiple hits therefore resolved into a distant, uncertain lead. Ancestry.com’s role in this episode is tied to the limits of interpretation as much as to the promise of database searching: an apparent match can suggest a direction without supplying an identity.

Database Scale and Genealogical Possibility

The book places the value of consumer DNA databases in direct relation to their size. By 2016, companies offered DNA testing for around a hundred dollars and a saliva sample. Their services could return previously unknown first cousins to adoptees or people raised by single mothers; those relatives could, in turn, help users learn about birth fathers and other parts of their identities. If a user had no match at first, companies might send an email when new relatives uploaded their DNA, so the pool of possible connections could grow over time.

At that point, the reported databases were substantial: 23andMe had 1.5 million profiles, while Ancestry.com had 2.5 million. The book’s proposed investigative logic follows the same family connections that consumer users might use for personal discovery. If law enforcement could compare crime-scene DNA against a large consumer database, a relative’s profile might point toward a perpetrator’s family. A cousin would not, by itself, identify the offender; it could instead provide a starting point for further genealogical work. The number of profiles mattered because it affected the possibility of finding such a relative in the first place.

That potential was not equivalent to actual investigative access. Neither Ancestry.com nor 23andMe would work with law enforcement, citing privacy issues and their terms of service. The large database could therefore be described as promising in scale while remaining unavailable for the proposed police search. Ancestry.com’s importance rests partly in that gap between what the data might make possible and what the company permitted investigators to do.

Contrast with Criminal DNA Systems

The book sets consumer genealogy databases against the government-led system built for forensic comparison. The DNA Identification Act of 1994 established the FBI’s authority to maintain a national database, and CODIS became the upper level of a system fed by local and state crime laboratories. Local labs entered unknown crime-scene samples and certain collected suspect samples into state databases; the state systems verified and compared them before passing samples upward to CODIS. In California, the account says, inputted samples were automatically uploaded every Tuesday, while the state also collected DNA from jails and courthouses.

The contrast is institutional as well as technical. CODIS was organized around criminal-justice collection and comparison; Ancestry.com’s profiles came from consumer testing and were governed by the company’s privacy commitments and terms. The book also describes how much forensic DNA technology had changed: when the Orange County Crime Lab began incorporating DNA testing in the early 1990s, a criminalist could spend up to four weeks on a case, and testing required a sizable, well-preserved sample. Earlier RFLP profiling was laborious, while later techniques could work from a smattering of skin cells in hours. Those advances expanded the investigative possibilities of DNA, but they did not erase the separate questions of database coverage, genealogical uncertainty, and permission to access consumer records. Ancestry.com thus stands at the boundary between genetic data’s capacity to connect people and the limits imposed on using that data for criminal investigation.