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Animal Forensic Lab Solves Human Cases

A dog’s urine sample helped identify and convict a man accused of attempting to sexually assault the dog’s owner.

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During the investigation of a man who fled after attempting to sexually assault a woman working in her front yard in Iowa in 1999, it was a dog’s urine sample—not the man’s face—that identified him as the attacker.

Despite that the victim was unable to identify her attacker in a police line-up, she did remember the vehicle he drove—and the fact that her dog had urinated on one of his car tires.

A urine sample, taken from what was suspected to be the perpetrator’s car, was sent to Elizabeth Wictum, director of the forensic division of the Veterinary Genetics Laboratory at the University of California, Davis, who confirmed the sample had come from the victim’s dog.

It was all the evidence needed to get a guilty plea from the attacker, and put him behind bars for two years.

No stranger to strange cases, Wictum has seen animal DNA provide enough evidence to put many criminals behind bars. And after working in the forensic lab since its opening in 1999, she’s seen just about everything.

“You never know what’s going to come through the door,” Wictum says. “You have to think outside the box.”

Each year, the service laboratory tests about 250,000 samples for parentage verification, coat color and disease diagnostics.

The forensic laboratory, however, tests fewer than 1,000 samples because of the increased security and documentation required, as well as the unusual nature of the samples, such as animal feces, blood, bone marrow, teeth, muscle tissue, hair and saliva—each of which were used to help solve crime cases, even some involving murder, Wictum says.

She says that, although she has testified in some cases taken to court, most defendants work out a plea agreement outside of court once they discover the lab has found solid animal DNA evidence against them.

“DNA is such a powerful tool,” she says. “More investigators are starting to use DNA.”

Forensic veterinarian Melinda Merck, DVM, of Atlanta, submitted dog urine samples to UC Davis’ forensic lab from a torture case where brothers were found guilty of putting a 3-month-old puppy in a gas oven where it burned to death. She says the evidence helped establish that the puppy was alive when it was put into the oven and confirmed timelines with witness statements.

Dr. Merck says that veterinarians should be involved at the beginning of these cases to recognize and interpret evidence found at the scene and on the animal.

“Vets need to report all suspicions of animal cruelty to the authorities,” Merck says. “They are on the frontlines to see abuse and may be the only ones who can stop it and protect the animal.”

It’s also important for veterinarians to know what kind of samples to take and how to take them, Wictum says.

They should collect buccal, blood or tissue samples (if the animal is deceased) from the pets involved, Wictum advises. In the event of a missing animal, DNA can be collected by securing bedding, chew toys, brushes and bowls that were used by that animal only.

Biological evidence can break down if not secured and kept cold and dry, she says, adding that it is best to contain the evidence in an envelope, not a plastic bag, unless the sample is being frozen.

Although recognized as a useful resource in animal abuse cases, animal DNA was once overlooked as evidence in human cases. Evidence collected from animals used to be set aside by investigators because police labs are only designed to test human DNA, Wictum says.

“Some animal samples have been collected at crime scenes, but never tested,” Wictum says. “We’ve been able to re-look at some of these and solve cases.”

One such case is the 1982 trial of Wayne Williams, a suspect in the Atlanta child murders who was convicted of two adult murders and sentenced to two consecutive life terms.

Dog hair that was collected and used as evidence against Williams in the trial is now being run through DNA tests by UC Davis’ forensic lab, and the pending results could have an effect on the case’s final outcome.

The reinvestigation is a part of The Innocence Project, a national litigation and public policy organization that, according to its website, is “dedicated to exonerating wrongfully convicted people through DNA testing and reforming the criminal justice system to prevent future injustice.”

Wictum says the advanced technology now available to run DNA tests on dog hair was not available at the time of the trial. Officials will use the evidence to determine whether Williams should be exonerated.

Technological advances make her job an ongoing learning process, she says.

“We’re constantly developing new protocols and techniques,” she says. “It’s a challenge.”

Wictum’s team faced one of its  biggest challenges when samples were received from an animal they had never worked with before—a bear. A man in New York accused of poaching claimed to have killed only one bear, although the samples collected appeared as though they had come from different sources. 

Without a bear DNA test in place, the forensic lab’s staff used resources at the university to find answers.

UC Davis’ Wildlife Research Group provided the forensics staff with bear DNA markers they assembled to determine that the samples collected were taken from two different bears.

Wictum says the lab also often receives cases of clients looking to recover  lost pets.

“We get letters thanking us for finding an answer,” Wictum says. “Even if it’s not the answer they wanted, [it helps them] go on.”

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