The dead girl had perfect teeth.

That’s what so many of the strangers who obsessed over her case online noticed, and one of the few things that could even be noticed. Her body was burned so badly as to be unrecognizable when she was found in the early hours of October 29, 2006, near Longview, Texas.

The two men who saw her thought, at first, that they had stumbled across a mannequin set on fire, perhaps as an early Halloween prank. It was the smell that alerted them to something more sinister in the woods—a smell like charred hot dogs. When they stepped closer, they realized the awful and obvious truth. A human being had been killed, then doused in gasoline and set on fire, and probably only minutes before: Her body was still ablaze.

When law enforcement came, the officials began making note of the few facts that would come to encompass her entire identity. She was young, between 17 and 25. She had semen inside her. She had blond hair with strawberry highlights. There was $40 in the pockets of the clothes she wore, a pale-purple shirt and jeans, size 7-8, branded One Tuff Babe. “Sadly ironic, considering her fate,” a commenter remarked on the true-crime discussion forum Websleuths. That same commenter would later give her a nickname of “Lavender Doe”—chosen for the color of her shirt.

Days passed, then weeks, and then years. No one who knew her name ever came forward. No friends or family called the sheriff’s office in Texas. No one filed a missing-person report. Lavender Doe, bestowed by an online stranger, was the only name she had.

This past November, 12 years and a month after she was found dead, I went on a road trip to Longview, Texas, with volunteers who believed they had just uncovered Lavender Doe’s real name. Seven months earlier, a genetic genealogist had led police to a suspect in the infamous Golden State Killer case, and volunteer genealogists with a fledgling nonprofit called the DNA Doe Project had helped Ohio law enforcement identify a murder victim previously known only as the Buckskin Girl.

Cold cases have always attracted amateur sleuths—and psychics and self-proclaimed forensics experts—often to the irritation of actual law enforcement. Genetic genealogy is different: It works. Once this combination of traditional genealogy and DNA tools led to the arrest of the suspected Golden State Killer, the floodgates opened wide. Self-taught genealogists were helping police identify criminals and victims almost by the week. Suddenly, it seemed, anyone with the right savvy and an internet connection really could solve cold cases from their living room.

The three genealogists I met in Texas were all volunteers for the DNA Doe Project: Kevin Lord, a 35-year-old with scraggly black beard then studying to be a private investigator; Missy Koski, 55, a “search angel” who helps other adoptees find their birth parents; and Lori Gaff, 49, a genealogy enthusiast with an encyclopedic memory and a particular recall of true-crime shows on Investigation Discovery. “I’ve seen almost all of them now,” she says, “so I’ve moved to the Food Network.”

The three had been feverishly exchanging Facebook messages—with one another and with a handful of other volunteers on Lavender’s case—but none had met in person until we convened in a parking lot outside Austin. Kevin and Lori both live near the city; Missy had driven up the night before from San Antonio. As they got out of their cars, they did the will-we-shake-hands-or-will-we-hug dance of strangers who were not quite strangers. They opted for hugs. “It’s so weird,” Missy said. “We stay up all night on our laptops and everything. My husband’s like, ‘Who are you talking to?’” She laughed. So this is what it’s like to meet the people you stay up late discussing murders with.

Clockwise from top left: Lori Gaff, Kevin Lord, and Missy Koski are all volunteers with the DNA Doe Project, a nonprofit that uses genetic genealogy to find names for unidentified bodies. (Miranda Barnes)

Over the past six weeks, the volunteers had traced the origins of the young woman they believed to be Lavender Doe back more than a century, all the way to Europe.