Issue Date: May 23, 2016
C&EN profiles the U.S. Fish & Wildlife forensics lab, the nation’s CSI: Wildlife team
The bald eagles—there were 13 of them—were discovered on Feb. 22, their corpses scattered on farmland in Maryland. At the scene, investigators found no obvious signs of physical trauma. But the unusual position of the bodies seemed to rule out natural causes.
The investigators flew the eagle carcasses to the U.S. Fish & Wildlife Service’s forensics laboratory in Ashland, Ore. The agency does not comment on cases under investigation, but the Maryland Natural Resources Police stated that the federal lab has ruled out natural causes, including disease. Now, the investigation has turned to human suspects. And causing the death of a bald eagle is a federal crime.
The case has attracted national attention. “It is a really unusual case,” observes Mike Parr, chief conservation officer of the American Bird Conservancy, an advocacy group. It seemed as though the eagles had abruptly fallen out of the sky. Parr says he is confident that the scientists at the Fish & Wildlife lab will identify what killed the birds. He and bird lovers across the country are anxious to learn the results.
The Oregon facility is the only full-service lab in the world dedicated to crimes against wildlife. Since it was established in 1988, the lab and its experts in chemistry, genetics, pathology, and other specialties have helped wildlife investigators by analyzing crime scene evidence. If their analysis links the victim, crime scene, and suspect, law enforcers use it to build a case that can stand up in court.
Just as in human forensics labs, the basis of science at the wildlife lab is to compare the unknown—the crime scene samples—to the known. For example, chemists analyze blood or stomach contents using chromatography to test for the presence of known toxics.
Yet in other ways, the job of wildlife forensics scientists is quite different. Often, the lab must determine the species of the victim—which is not an issue in homicides. When an entire carcass is available, the identification may be fairly simple. But the lab also tests animal parts and products imported from around the world that law enforcement officers suspect came from illegally killed, often endangered, animals.
Wildlife investigations present special complications, lab director Ken Goddard points out. “Not every killed animal represents a crime. It usually depends on the species and may depend on time of day or place of death because of hunting laws, for example. We could also have an animal as a perpetrator as well as a victim.”
After the lab was established on paper in the 1980s, advocates worked to get federal funding on the basis of the idea that DNA, which was getting more use in human forensics, could be used to nab perpetrators of crimes against wildlife. The lab’s analytical know-how also helps enforce the Lacey Act, which bans trafficking in illegal wildlife; the Migratory Bird Treaty Act; and the Convention on International Trade in Endangered Species of Wild Fauna & Flora.
It’s about 10 AM on a recent Tuesday when the lab’s intercom announces that FedEx has delivered evidence to the receiving door. Evidence arrives in cardboard boxes and hard-sided coolers and in various states of freshness or decomposition. Each year, the lab generates and analyzes roughly 12,000 samples gathered by wildlife law enforcement investigators in the field.
Colleen Wilson is in charge of evidence control, so she handles unpacking the delivery, which comes wrapped and on ice in a cooler. She explains that the body is in good condition and easy to identify: The large, dark-feathered bird with an impressively large wingspan is clearly a California condor, which is a critically endangered species. Still, the lab’s ornithologist will make the official ID.
Only about 5% of the evidence that comes to the lab is an intact carcass like the ill-fated condor. In fact, only about half of the material coming to the lab is a dead animal or part. The other half consists of finished products—crocodile skin shoes, tortoiseshell or rhinoceros horn accessories, caviar from protected sturgeon, traditional medicines made from the organs of rare species.
When the animal is difficult to identify, the evidence is sent to the lab of Barry Baker, section head of the morphology department, which studies the form and structure of animals. Baker’s team gets whole animals, animal parts, hair and feather samples, and finished products. It uses visual inspection, microscopy, and spectroscopy tools to determine if an item is made from an animal and, if so, what species.
“Once you have a broad enough perspective based on experience, you can tell if a suspect item is made of sea turtle shell, for example,” Baker says. Those suspicions are confirmed by testing and comparison to a huge database of microscope images and spectral data from known samples.
The lab must use protocols that are scientifically valid and will withstand judicial scrutiny. Goddard helped form the Society for Wildlife Forensic Science to collect, validate, and share methods and tools with similar labs in states and other countries. With few specialists working in wildlife forensics, the Fish & Wildlife scientists often take the lead by doing their own research and publishing their results in journals.
For example, Baker helped develop a process to identify the origin of products, such as hair combs, that appear to be made of tortoiseshell. An item with characteristic speckled amber and brown hues may have been made from cheaper dyed cow horn, which, like a turtle’s shell, is formed from keratin.
Baker and colleagues tested a process that uses diffuse reflectance infrared Fourier transform spectroscopy. When the resulting spectra were further analyzed with a statistical tool based on discriminant analysis, they found they could correctly determine which species supplied the keratin (Archaeometry 2007, DOI: 10.1111/j.1475-4754.2007.00328.x).
Baker’s lab can also determine if a product is made from a species of protected rare wood such as ebony or rosewood. The team has developed a process using direct analysis in real-time mass spectrometry, or DART-MS. In a test using DART-MS, a sample of wood is placed in a stream of hot helium gas that ionizes the surface. The mass spectra from the ions can be compared with samples in the lab’s wood library.
But Baker’s lab’s tools have limits. Hand him a crocodile skin belt, and he can’t say which species of croc supplied the material. He’ll send the belt to Dyan Straughan and her colleagues in the genetics section, for whom identifying a reptile based on skin is a comparatively easy task. They also obtain and analyze DNA from trickier samples such as pasteurized caviar, antler, bone, and ivory.
In addition to species identification, scientists can use DNA to identify an individual animal and, for example, match a sample found on a person or vehicle to material found at a crime scene. “Individual matches are more difficult—you need lots of references because of the variations within a particular species,” Straughan says. The genetics team is busily growing its library of 60,000 reference samples.
The geneticists are commonly called on to identify a specific individual or a member of a regional population when the victim is a North American animal such as a coyote, a wolf, an eagle, a cougar, a bobcat, an elk, a moose, or a deer, Straughan says.
The condor’s species, however, is not a mystery, so after Wilson unpacks it, she sends it to the pathology department. Chief pathologist Tabitha Viner first takes an X-ray of the bird to scan for metal objects such as bullets or shotgun pellets. She finds none but does spy a tiny internal microchip that will identify the individual bird.
Then she lays the large vulture on a steel table for a postmortem exam. Sometimes the X-ray or necropsy will show a cause of death, Viner explains, but tissue and fluid samples will be further analyzed.
“We don’t assume there is just one cause of death,” Viner says. Recently, the lab examined a wolf that had been shot but was also suffering from distemper. “A disease or toxin that doesn’t itself kill the animal may change its behavior and put it in the way of danger,” she explains.
Viner proceeds to carefully skin the condor with a small blade. “Birds are always wearing clothes,” she says. “To see any bruises, we have to take the skin off.”
After pulling away the skin, Viner points to the condor’s large crop—a bumpy, darkly mottled organ near the base of its long neck. The crop, which often contains stones or grit the bird ate, helps the animal break down difficult-to-digest matter, including large bites of carrion. She explains that condors are highly sensitive to lead poisoning, which affects the appearance and health of the crop, although she declares this one to be healthy-looking.
Viner takes samples of the contents of the crop and stomach as well as blood and urine and slices of liver and kidney tissue to be tested for chemical residues. She will examine the tissue under a microscope for signs of bacterial or viral disease. If a case hinges on time of death or location, the lab will take samples of insects, pollen, and soil found on a carcass.
In the lab’s chemistry department, the scientists check if an animal was exposed to a toxic substance at a level that could have contributed to its death. Using a host of gas chromatography and mass spectrometry tools, they compare samples with a panel of about 40 chemical suspects. The panel includes common agricultural pesticides such as organophosphates and carbamates, rodent poisons such as strychnine and anticoagulants, and agents such as 4-aminopyridine designed to control bird pests.
“We can know by the peak in the mass spec the type and level of a pesticide in organs and fluids,” Goddard says. The information helps the pathologist figure out, for example, if the animal’s death was due to ingestion of poison contained in a rodent part found in the stomach.
Given the large number of potential samples to test, fully investigating a case like the condor’s could take six months to a year, Goddard says. When the pathology department can’t determine the cause of death, it will hold samples in the hopes that future technologies and techniques can return results, Viner adds.
Despite a heavy workload, the wildlife lab’s scientists are driven by difficult cases and the occasional unsolved mystery to do research, expand their libraries, adopt new tools, and develop new methods.
For example, Viner is waiting on delivery of a combination X-ray and CT scan instrument. It will be the first ever used to provide three-dimensional images of animal victims. Baker says a new scanning electron microscope will help him compare difficult hair samples.
The geneticists recently took possession of a high-throughput KingFisher DNA purifier from Thermo Fisher Scientific to tackle a backlog of reference samples. And with a new next-generation sequencer, the team can do things such as isolate a wolf’s DNA from a bite on a lamb.
“We have access to a lot of expensive scientific tools here and so can really push the envelope,” Goddard says.
Although only a small percentage of wildlife cases go to trial, when they do, the lab’s scientists may be asked to provide unbiased testimony in court about their findings.
“Our job is simply to explain and interpret what the evidence says, can say, or doesn’t say,” Goddard says. “We take care not to learn much of the case background and make it a point never to call to ask how the case turned out.”
Staying in the dark will be hard in the case of the Maryland bald eagles, which is of great interest to wildlife advocates across the country.
They know that the Fish & Wildlife Service recently investigated the case of a New York produce farmer who, wanting to kill coyotes, placed meat laced with methomyl on the edge of a cornfield. The illegal use of this carbamate insecticide, which is toxic to humans and wildlife alike, caused the death of three juvenile bald eagles. The farmer was fined $1,000 and put on probation for six months.
But finding 13 dead eagles at once is unprecedented. “Any information we can get about the eagle deaths is critical,” says the American Bird Conservancy’s Parr. “I’ve been doing this work for 20 years, and I can’t think of anything like it.”
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