Alain Frantz is a population geneticist—not a detective or policeman or forensics expert. But he often works on game animals, like deer and badgers, which naturally leads to working with collaborators who work with hunters. And that is how the mystery of the dead hunting dog fell into his lap.
The terrier was bleeding on the forest floor, shot through the chest, after a group boar hunt in Germany. No one would admit to shooting the dog—even on accident. “In the cold light of day,” said Frantz, “it’s an insurance question.” Hunting dogs, purposely bred and highly trained, are worth thousands of dollars, and the owner had a legal claim to compensation. People wanted to know.
The poor dog, meanwhile, was rushed into emergency surgery, which did not save its life but revealed a significant clue: several wild boar hairs embedded in its gunshot wound. Catch dogs are trained to pin boars down for the hunter to kill. The hairs likely came from a boar it had grabbed onto—and the bullet that killed the boar probably also killed the dog. Finding out who shot which boar was trivial: Each boar is harvested and taken by its hunter.
The missing link was whose boar those hairs belonged to. Frantz had previously studied the genetic diversity of wild boars that go around terrorizing the city of Berlin. Could Frantz, who now worked for Luxembourg’s National Museum of Natural History, help identify this boar down to the individual? He agreed to try, and his German collaborators gave him the collection of physical evidence: six boar hairs from the dog’s wound and muscle samples from all 19 boars harvested that day, preserved in alcohol.
Forensics labs match human DNA samples all the time, but they don’t sequence the entire genome—that would cost thousands of dollars per sample. They do, however, look for a specific regions of high variability known as genetic markers. Test enough markers, between one and two dozen, and you can have near 100 percent certainty that the DNA belongs to any individual person. This is easy in humans because we know a lot about variations in human DNA.
Wild boars? Not so much. Here, Frantz had a major assist from the U.S. pork industry. In the 1990s, geneticists at the U.S. Department of Agriculture did the painstaking work of identifying hundreds of genetic markers in domesticated pigs—for pig breeding purposes, of course. And it turns out that domesticated pigs and wild boars are closely related enough that scientists can use some of the same genetic markers. Frantz took 13 markers and tested all 19 boar samples against the hair. And sure enough, he had a perfect match for all 13 markers: sample S6070. The results are published in the journal Forensic Science, Medicine, and Pathology. (Thanks to Ivan Oransky who first brought it to my attention.)
Wildlife forensics is often reliant on the kindness of scientists studying more common animals. At the U.S. Fish & Wildlife Service Forensics Laboratory, Dyan Straughan says that the wolf markers she uses originally came from dogs. She also has a rigorous system for calculating the probability if a sample is a true match. If, for example, the individual wolf she’s trying to identify is in Wyoming, she has to compare it to 30 to 50 wolves specifically around Wyoming. That’s because different populations can have a slightly different makeup on genes. And since the lab gets samples from all over the country, that means a reference set that includes wolves from all over the country. “In the wolves, I have a thousand individuals that cover the wolves in the Great Lakes, the wolves in the western states, the Mexican wolves, red wolves, and so forth,” said Straughan. “I have a really large database.”
The U.S. Fish & Wildlife Service Forensics Laboratory has these standards because it provides evidence for court in wildlife crimes. Most of the work involves identifying just the species—often endangered ones—but sometimes investigators want to identify the individual animal involved, like if they want to match a carcass to a mounted elk head. “You have meat in a freezer or blood on a knife or on pants in the car or something like that, and you can match those back to the gut pile,” said Straughan.
In the case of the hunting dog, Frantz wasn’t trying to provide evidence for court. “Because it wasn’t the police that took samples,” he said, “you couldn’t have gone to court with it." The study was really a proof of concept. The forestry commission in Germany that had organized the boar hunt wanted to put out a warning: If you shoot a dog in a forest and no one sees it, we will still find you.