With aid of DNA analysis, dog detectives have perps on the run
By Sandy Robins
updated 11:15 a.m. PT, Fri., April 29, 2005
Picture it: Eight men of assorted shapes and sizes standing in a typical police lineup. But in this scenario there is no nervous witness or victim watching from behind a one-way glass, hoping to identify a face and link it to a crime.
Instead, the door opens and in bounds a large Alsatian. The dog runs in between the men, sniffing. Within minutes, he sits down in front of one of the suspects, his tail wagging as he barks his confirmation.
Once the dog has pinpointed the perpetrator, thanks to his amazing olfactory capabilities, law enforcement officers take over and the CSI (canine scene investigator), gets a tasty reward for a job well done.
The nose knows
While they don’t yet have their own network TV show, canines are increasingly becoming recognized crime technicians. There’s no doubt about it — the nose knows. And “scent-line-ups” are becoming more common as these highly trained dogs play a growing role in crime investigations.
Like most dogs, canine scene investigators are capable of making a fine distinction between scents. They can get a “scent picture” of one scent even when other scents are present. It’s been said that when a dog walks into a bakery, he doesn’t smell cake, but the flour, eggs and butter.
“Dogs are great detection tools,” says Liz Burne, a canine trainer, who, together with her springer spaniel Lionel, a search-and-rescue dog, has worked many successful cases with the Connecticut Canine Search and Rescue team.
Search-and-rescue dogs are divided into two kinds: air-scenting dogs and trailing dogs. Air-scenting dogs are trained to find any human scent, explains Burne. “Consequently they can locate and alert their handler to any human in the search area.”
Humans are natural scent generators — they emit odors through respiration, perspiration and the shedding of skin cells and hairs. Air-scenting dogs work off-leash and can trace a human scent without the aid of an article that was worn or handled by the subject of the search.
The advantage to air-scenting dogs is that there is no need to keep the search area clear of other searchers. If there are other searchers in the area, the dog will find them, be rewarded and sent out again until they locate the intended scent source, which is the person alive, dead, or even under water.
Hot on the trail
In contrast, trailing dogs are “scent specific” and will follow the path the subject traveled rather than trace a scent to its strongest point, explains Burne. They start off with a scented article, typically an item of clothing recently worn by the subject, and track the scent to the subject’s location.
To assist them in their work, human crime scene investigators often use a “scene sleeve,” a special receptacle that captures and contains the odor. This allows the scent to be transported, usable for multiple dogs and preserved for future use, such as scent lineups.
Despite their amazing olfactory skills, there are limits to dogs’ usefulness at crime scenes. “While dogs can be sent into the field wearing a GPS tracking device, I can’t ever envisage Lionel in little latex booties marking things with flagging tape,” says Burne. “Dogs are trained to give a passive alert, typically sitting or laying down next to the evidence. This keeps them safe. It would be dangerous having them retrieving evidence, like a gun, and disturbing crime scenes.”
While many people think that all canine scene investigators do basically the same job, their work is in fact highly specialized. Apart from air scenting and trailing, they are also trained to detect narcotics, bombs and other explosive devices, and arson accelerants. They can work in all types of terrain from water to treacherous avalanche conditions.
Capt. Scott Shields, formerly of the New York City Urban Parks Search and Rescue Team, is someone who truly understands canine detection capabilities. Together with his canine partner, Bear, a golden retriever, Shields led the first canine search-and-rescue teams at the World Trade Center after Sept. 11. Bear, who became America’s most decorated dog, was wounded at Ground Zero and died in 2002 from multiple forms of cancer resulting from his work at the site.
Shields went on to found The Bear Search and Rescue Foundation to provide training, equipment and transportation to search-and-rescue teams around the country.
“Dogs are able to key in on samples of human tissue and remains that investigators can miss,” says Scott. “Fortunately, as a result of the World Trade Center disaster, more influential people in the world of forensics now understand the value of canine investigators. Nevertheless, the work these dogs do would be meaningless without the scientific advances made in DNA matching.”
Witnesses to a crime
Time and again, DNA analysis has proved to be the key to a crime and now the spotlight is on a relatively new branch of this forensic science — animal forensics. This technique allows animals, particularly dogs and cats, to become reliable witnesses to a crime.
Using DNA technology, the Veterinary Genetics Laboratory at the School of Veterinary Medicine at the University of California, Davis, is a world leader in identifying animal evidence at crime scenes. By analyzing dog and other animal hair, saliva and various tissue samples left at a crime scene, criminologists have been able to use animal evidence to link a suspect to a crime.
One of the most publicized animal forensic cases was the murder of 7-year-old Danielle van Dam in San Diego County in 2002. Dog hair found at the home of murder suspect David Westerfield turned out to belong to the dog owned by the van Dams and became a vital piece of the puzzle linking Westerfield to the death of the girl.
Dr. Sree Kantihaswamy, director of VGL Forensics, the animal forensic genetics unit at the Veterinary Genetics Laboratory, has been performing animal DNA analysis since 1996. Recent requests from federal, state and local law enforcement agencies have increased more than 100 percent, says Kantihaswamy.
“Human forensic scientists are learning to think more outside of the box,” he says. “If they see something that doesn’t appear human, they are preserving the evidence under the same stringent conditions and sending it to us for analysis. Consequently animal DNA is playing a more important role in crime solving than ever before.”
Given that the latest figures released by the American Pet Products Manufacturers Association show that more than 69 million U.S. homes have cats and dogs, animal DNA analysis could make it even more difficult for criminals to get away with their crimes.
But apart from identifying animal witnesses, animal forensics can also confirm them as the perpetrators.
City officials in Dresden, Germany, tired of having their sidewalks littered with dog doo, have decided to crack down on owners who are not scooping. They’ve proposed a law that would require all licensed dogs to give saliva samples for analysis. The city hopes to use this DNA to identify sidewalk offenders.
Sandy Robins is a freelance writer and columnist based in Irvine Calif. Her work has appeared in numerous publications in the United States and internationally.
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