Should Cops Use Family Tree Forensics? Maryland isn’t so Sure

Police departments around the country are getting increasingly comfortable using DNA from non-criminal databases in the pursuit of criminal cases. On Tuesday, investigators in North and South Carolina announced that a public genealogy website had helped them identify two bodies found decades ago on opposite sides of the state line as a mother and son; the boy’s father, who is currently serving time on an unrelated charge, has reportedly confessed to the crime. It was just the latest in a string of nearly two dozen cold cases cracked open by the technique—called genetic genealogy—in the last nine months.

This powerful new method for tracking potential suspects through forests of family trees has been made possible, in part, by the booming popularity of consumer DNA tests. The two largest testing providers, Ancestry and 23andMe, have policies in place to prevent law enforcement agencies from directly accessing the genetic data of their millions of customers. Yet both companies make it possible for customers to download a digital copy of their DNA and upload the file to public databases where it becomes...