Tuesday, September 7, 2010

Hair of the Dog Bites Even After Dog Can't: Canine DNA Becomes a Forensic Tool

Human DNA testing has become a major forensic tool since 1985, but animal DNA testing is also proving useful. In 1998, the FBI created the national Combined DNA Index System (CODIS), a database of DNA profiles of convicted criminals. The first use of DNA profiling on an animal that led to forensic evidence involved a cat. The police found a leather jacket spotted with a murder victim’s blood on Prince Edward Island. There was no evidence linking the key suspect (the estranged common law husband of the victim) to the jacket, but numerous strands of cat hair were found on the jacket. Genotyping verified that it was hair from the cat that lived with the suspect. This was enough of a link to convict the suspect. Menotti-Raymond, M., Davis, V., and O’Brian,S. (1997). Pet Cat Hair Implicates Murder Suspect. Nature, 376, 774.

In 1991, a 68 year old man was beaten to death in Vernon, British Columbia, as was his dog. Blood samples were saved from both. Blue jeans and a sweater were collected from a suspect but no charges were filed. In 1996, the case was reopened. Blood on the sweater was found to match that of the deceased, and blood on the jeans to match that of the dog of the deceased. The case was described in a scientific paper as coming to a successful conclusion, presumably a conviction. Shutler, G.G, Gagnon, P., Verret, G., Kalyn, H., Korkosh, S., Johnston, E., and Halverson, J. (1999), Removal of a PCR Inhibitor and Resolution of DNA STR Types in Mixed Human-Canine Stains from a Five Year Old Case, Journal of Forensic Sciences, 44(3), 623.

In a case arising in the state of Washington, two men were shot to death in their home by gang members looking for drugs. Leuluaialii and Tuilefana were convicted of aggravated murder and animal cruelty for shooting the victims’ dog, Chief. Gang members who helped the murderers search the house testified to their own involvement, but denied any connection to the murders. When Leulauialii was arrested, three jackets were found, two of which had hair with characteristics similar to Chief’s hair. DNA testing was conducted on the hair. The defendants requested a Frye (293 F. 1013 (DC Cir. 1923)) hearing on the diagnostics which found statistically significant matches of markers of the dog hair found on the defendants’ coats and Chief. The trial court held such a hearing was not necessary. The appellate court disagreed, saying:

"The evidence here clearly involved novel scientific theory: the forensic identification with high statistical probabilities of a specific dog through analysis of canine DNA. There are no published United States cases that involve the use of canine DNA markers for forensic purposes or examine the validity of the specific markers used here. A Frye hearing was absolutely necessary in the present case."

The trial court, according to the appellate decision, should have determined if (1) the scientific theory behind the testing results has general acceptance in the scientific community, (2) the techniques and experiments to produce the results are generally accepted by the scientific community, and (3) the laboratory performed accepted scientific techniques. The appellate court, reviewing the evidence and the primary research involved, was not convinced that there was general acceptance of the first two factors. The court acknowledged that research indicated dogs have genetic diversity as humans, The court held that the specific markers and probability estimates as to the frequency of matches had not been published. Therefore, the standard for admission of the evidence was not met. Nevertheless, the court found that other evidence was overwhelming and the error was deemed harmless. Washington v. Leuluahialii, 118 Wash.App. 780, 77 P.3d 1192 (Wash.App. Div.1 2003), petition for review denied, 154 Wash.2d 1013 (Wash.Sup.Ct. 2005); habeas corpus petition denied, Leuluaialii v. Sinclair, 2010 WL 891015 (W.D. Wash. 2010).

The decision had a chilling effect on other canine DNA evidence that could have been presented in other prosecutions. Kanthaswamy, S., Development and Validation of a Standardized Canine STR Panel for Use in Forensic Casework (April 2009) (report submitted but not published by the Department of Justice, made available by National Criminal Justice Reference Service). Kanthaswamy notes that canine DNA may link a suspect to a crime scene or to a victim, or a victim to a crime scene.

Canine DNA research has reached a level where the Leuluahialii court should now be satisfied that there is sufficient acceptance in the scientific community for the admission of such evidence. Although the number of labs doing this kind of work remains small, the results are solid and should satisfy the version of the Frye scientific evidence standard used in many states (or the Daubert standard for that matter, Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579 (1993)). Cassidy, B.G. and Gonzales, R.A. (2005). DNA Testing in Animal Forensics, Journal of Wildlife Management, 69(4), 1454-1462. See also Halverson, J.A. and Basten, C. (2005). A PCR Multiplex and Database for Forensic DNA Identification of Dogs. Journal of Forensic Sciences, 50, 1-12.

In a case of arson in which the defendant was charged and convicted of killing his two-year old daughter, for whom he did not want to pay child support, part of the evidence was a threatening note that the defendant sent. A hair on the envelope was found, through DNA testing, to be “1,100 times more likely to have come from [the defendant’s] dog than any other dog.” There was no other discussion of the DNA evidence. Treiber was sentenced to death, which was affirmed on appeal. Pennsylvania v. Treiber, 582 Pa. 646, 874 A.2d 26 (Pa.Sup.Ct. 2005), aff’d 970 A.2d. 484 (2009).

For a recent legal summary, see Imwinkelried, E.J., Canine DNA (2010), a working paper posted on SSRN. (Thanks to a reader for notifying me of this important paper.)

Even after both are dead, a dog can still get justice for his master.

Addendum. DNA is also being used to identify dogs in dog bite cases. See Eichmann, C., Berger, B., Reinhold, M., Lutz, M., and Parson, W. (2004). Canine-Specific STR Typing of Saliva Traces on Dog Bite Wounds. International Journal of Legal Medicine, 118(6), 337-42; Clarke, M., and Vandenberg, N. (2010). Dog Attack: The Application of Canine DNA Profiling in Forensic Casework. Forensic Science, Medicine and Pathology, 6(3), 151-7 (September 2010).

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