In a higgledy-piggledy complex of tired-looking trailers parked alongside grain silos and stock pens, four white-coated scientists are investigating crimes with the tools of 21st century forensics. They’re testing hairs found on a blanket wrapped around a victim of rape and murder, trying to match them to a suspect’s dog. They’re analyzing the DNA of two Pekingese killed during a robbery to determine if a suspect was at the scene of the crime. They’re looking for a match between stray hairs left at a murder scene and DNA taken from the suspect’s cat.
It’s all in a day’s work at the forensics division of the Veterinary Genetics Laboratory at the University of California at Davis, the CSI of the four-legged world. The humble surroundings bear only slight resemblance to the flashy labs you see on TV crime shows, but the division’s record of success reads like a Hollywood script. In its first year of operation, the lab helped prosecutors win a tricky sexual-assault conviction in Iowa in which the key clue was dog urine (the victim was unable to identify the suspect, but her dog had relieved itself on his truck during the assault). “Once we had the DNA to connect him to the crime scene, he pled guilty,” says acting lab director Beth Wictum.
The forensics lab was established in 1999 out of necessity. The university’s genetics lab, which specializes in verifying horses’ lineages, was getting more forensic requests than it could handle. “Police labs are only set up to do human work, and they were overwhelmed with that,” Wictum says. “If they had animal evidence, they would just set it aside.”
Yet animal DNA can sometimes mean the difference between a conviction and an unsolved crime. In a 2001 sexual-abuse case, a 14-year-old mentally handicapped boy told police he had been molested by a man who was licked by his dog during the act. Scientists tested DNA taken from the suspect’s skin and found the dog’s saliva exactly where the boy had said it would be. The molester pled guilty and got three years in federal prison.
There are other private and university labs that do forensic DNA testing of pets and farm animals, but none are as big or as busy. The Davis lab boasts the largest database of domesticated-animal DNA in the U.S.–including samples from 1.5 million horses, 25,000 dogs and a barn full of other species, from cows and goats to llamas and alpacas. Last year it fielded roughly 60 criminal cases, plus another 40 or so from insurance companies (typically trying to identify animals that caused property damage) and private citizens (usually wanting to know if the remains found by a road belong to their lost pet or whether the neighbor’s dog killed their cat). “For many people, pets are part of the family,” says Wictum. “You want an answer. You want justice.”
Getting answers from animal samples is often easier than extracting them from humans. Many pets are fastidious groomers, and the saliva covering the fur they shed makes it a far better source of DNA than snippets of human hair. The lab has also developed reagents specific to certain animals, making it harder for a sample to be hopelessly contaminated by, say, a scientist’s sneeze.