True Tales of Canine CSI
Investigators turn to dog DNA to convict criminals and acquit the innocent.
D. Caroline Coile, Ph.D.
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One of the most interesting, and sometimes controversial, uses of canine DNA is to link suspects to victims. Such was the well-publicized case of the murder of 7-year-old Danielle van Dam in San Diego County, Calif., in 2002. One of the pieces of evidence was dog hair found in the suspects motorhome. DNA analysis showed that the hair matched the little girls Weimaraner, suggesting it may have been carried into his home on her clothing.
Its not only the victims dog that can transfer DNA to the suspects belongings. The suspects dog can also supply the telltale DNA. Take the case of the dismembered body of a woman found in several trash bags in a lake. Dog hair found on the tape used to close the bags yielded DNA that matched her ex-husbands dogs. He was convicted.
Any dog owner knows that it is virtually impossible to enter an environment shared by a dog (however briefly) without picking up dog hair. They may not realize, however, that they themselves will consequently drop dog hairs wherever they go.
Although hair is the most common source of canine DNA evidence in crime investigations, DNA can also come from blood, urine, feces, semen, bone, teeth, muscle, and internal organs. Gang members invaded a home and murdered a young couple. The couples dog attacked the invaders, but was also shot at close range and killed. DNA from bloodstains on the suspects clothing matched the dog, linking them to the crime scene.
When dogs mark with urine they leave a distinct calling card for other dogs, but they also leave one for DNA experts. A rape victim noticed her dog urinating on a hubcap of her attackers pickup during the attack. Police swabbed the tire of their suspect and found a perfect match despite the suspects claim that he had never been near the victims home or dog.
In another case, stepping in a dog pile caused more than just a nuisance for one suspect. Three construction workers were found murdered in a home, but little evidence could place the suspect at the scene. However, the suspects shoes had dog droppings on the sole that matched droppings found in the walkway of the home where the murders occurred. The suspect, who had denied being at the home, was convicted.
Although courts are accustomed to the use of human DNA as evidence, the use of animal DNA is still relatively uncommon. Only in 1998 was such evidence first used in a United States courtroom (although cat DNA had been used a few years earlier in Canada). Police were investigating the killing of a Seattle couple and their dog, but had only minimal evidence against their main suspects. An investigator struck on the idea of contacting Dr. Joy Halverson, a veterinary geneticist who had done extensive work using DNA to verify pedigrees. Halverson tested the dogs blood against blood found on the suspects clothing and testified that it matched, helping to convict both suspects.Page 1 | 2 | 3 | 4
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