The case, which will be outlined in the November issue of the journal Forensic Science International: Genetics, could set a precedent, such that pet hair may be more commonly introduced as evidence in U.S. trials.
"Dog hair has been used in both state and federal courts," co-author Beth Wictum told Discovery News. "Cases range from animal theft to animal cruelty, murder, sexual assault, bestiality, and pretty much anything you can think of."
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| Henry Lee Polk, convicted of murder |
Wictum, who is associate director of the Veterinary Genetics Laboratory Forensics Unit at the University of California at Davis, and her colleagues analyzed the single light orange-colored cat hair that was found in one of the victim's jean pockets. The individual, from Clay County, Missouri, was found severely beaten with his throat violently lacerated to near decapitation.
Both the victim and the primary suspect lived with cats, so the cat hair by itself did not mean much, given how frequently felines shed. As any cat owner knows, strands of cat fur seem to wind up everywhere. Prior studies have demonstrated how shed cat hair can cling to everything from curtains to clothing.
The researchers therefore obtained and sequenced mitochondrial DNA (mtDNA) from the single hair. This is a type of DNA that passes down from mothers to their offspring. Another type of DNA, nuclear, provides more information because it encodes for the majority of the individual's genome.
"Shed hair usually doesn't have nuclear DNA because it is in the hair follicle, so we test the mtDNA in the hair shaft," Wictum explained. "However, because cats and dogs groom themselves, we sometimes get nuclear DNA profiles from shed pet hair."
For this case, only the mtDNA was available, but the researchers were able to compare and contrast it with mtDNA from a large general database as well as from samples of fur obtained from both the victim's and the suspect's cats. That was quite a challenge, since the suspect lived with 11 cats, and 8 of those were reported to be related.
The scientists, however, were able to exclude that the hair originated from the victim's cats, but it could not be excluded from the cats living with the suspect, who claimed that the victim owed him money for carpet installation.
The suspect was found guilty of first-degree murder, due to cat hair mtDNA and other evidence, and was later sentenced to life in prison without parole.
Criminal profiling expert Wayne Petherick of Bond University told Discovery News that he was not shocked that such evidence was accepted by a U.S. court, "but I was surprised it had taken as long as it had. It was really only a matter of time."
He said that human hair is more commonly presented as evidence, but he believes that as mtDNA databases increase in size, pet hair as evidence will strengthen.
University of Leicester forensic scientist Jon Wetton agrees, but added that "it is currently an expensive specialist test which cannot offer strong evidence, so its use will be limited to high profile cases where more conventional approaches have failed to build a strong enough case."
Wetton and his colleagues, however, have created the U.K.'s first cat DNA database. Cat hair was used as evidence in a case in the U.K. last year. It has also been used in casework in Canada, Austria and Belgium.
Wetton said, "As more countries accept cat DNA as admissible evidence, I am sure that its use will become more commonplace as pet hairs are frequently recovered when taping evidential items."
(Discovery.com - Sept 28, 2014)
ORIGINAL STORY:
Cat Hair Leads To Charges In Murder Of Contractor
MISSOURI -- Cat hair helped investigators bring charges against a Kansas City man in the murder of a self-employed contractor last year.
Henry Lee Polk, 40, is accused of first degree murder and armed-criminal action in the death of Stephen M. Nolte.
Nolte was found dead by a relative at a home he was working on in the 5500 block of North Troost on March 8, 2004.
Investigators found cat hairs on the victim's pockets that had been turned inside out.
Officers learned that Polk kept several cats at his home.
The hairs from the crime scene were sent to a California laboratory.
"The results of these tests indicated a genetic DNA match between a hair found on the victim and two of the cats from the Polk residence," Clay County Prosecutor Daniel L. White said in a press
release.
According to court documents, a witness told investigators that Polk went to the home on North
Troost on March 7, 2004 to talk to Nolte about money he was owed for installing carpet for him.
The witness also told investigators that Polk later took Nolte's pickup truck and dropped it off in
Kansas City, Kan. Two days after the murder, the witness claimed Polk had her drive him to a spot
in Liberty where she saw him burn clothing that he was allegedly wearing the night of Nolte's
murder.
Polk is being held on $300,000 bond.
(KMBC - January 21, 2005)
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