scientist compares skulls of different animals

The U.S. Fish & Wildlife Service Forensics Laboratory does many things you may be familiar with from those TV crime-lab shows, such as determining the cause of a death or checking whether the blood on a suspect's clothes is that of the victim. The difference is that the victims in this case are animals, which can make the job more complicated in lots of interesting ways.

The Only Lab of Its Kind

As the only lab in the world dedicated to crimes against wildlife, the facility supports the enforcement of federal wildlife laws. The most familiar of those laws is the Endangered Species Act, which currently protects 1,925 species of plants and animals. Other regulations protect migratory birds and marine mammals, and America's oldest wildlife protection law, the Lacey Act, passed in 1900, regulates plant and wildlife commerce between states.

Many of the lab's procedures mimic those performed in cases of crimes against humans. "If we extract from a dead animal that is protected — let's say a wolf — a particular type and model of bullet, and the main subject of the investigation happens to have a weapon that can fire that type and caliber of bullet, then we can seize the weapon, test-fire it, and make a determination of whether the bullet found in the wolf came from the subject's weapon," says Ed Espinoza, the lab's deputy director.

Other cases involve testing stomach contents for poison. "There are cases in which there are huge mortalities of migratory birds and raptors because people put out poison to kill, say, coyotes, and as a consequence kill endangered or protected animals," Espinoza says. Just like in a suspected human poisoning, the lab needs to scientifically determine the exact cause of death.

Identifying the Victim

There's one way human crime labs have it easier: They only have to deal with crimes against one species. When wildlife is involved, sometimes the first question is whether in fact a crime has been committed, since the laws apply only to certain species. And the identity of the victim maybe not be obvious, because the evidence may be only parts of the animal, which may be altered in various ways: as a leather purse, an article of clothing, an ivory carving or even a traditional medicine.

In those cases, the first line of defense consists of special agents and wildlife inspectors who are trained to identify suspicious items. "They not only need to know the law, they need to be able to do species identification on the spot, or identification of parts of species that may otherwise not resemble the whole animal — to tell ivory from plastic or bone, to identify endangered birds by the pattern in their plumages," Espinoza says .

The lab's job is then to confirm or deny that a protected species is involved, using a range of scientific tools and a staff that includes not only experts in chemistry, pathology and genetics, but also a herpetologist, an ornithologist and a mammalogist.

a post mortem exam of an oiled bird

Scientists at the lab have methods of dealing with materials that have been altered in appearance. "There are ways that we can see through dyed material in which they've tried to cover the pattern of the skin of a snake," Espinoza says. "We use tools that penetrate the dye, so we can see the pattern and make the species ID." They're also expert at testing and analyzing DNA in materials that are old or processed in various ways, like tanned leathers, or are body parts without the best DNA samples to begin with — like bone. "If you were to take a piece of meat from the butcher and sequence for the species, you'd be looking at 600 base pairs. That's a big chunk of DNA," Espinoza says. "But if you were to do the bone of that very same animal, you'd be lucky to get 250 to 300 base pairs."

Solving Cases

The lab has been part of high-profile cases like the BP oil spill in the gulf of Mexico in 2010. "All of the birds that died in the oil spill came here for determining cause of death — and determining that the oil in fact came from the Macondo well," says Espinoza, referring to the site of the infamous spill.

Even when the lab finds that no crime was committed, it's often for interesting reasons — sometimes, because people didn't get what they paid for. "Many times, people think they have ivory and it turns out to be bone," Espinoza says. In some cases, traditional medicines that are supposed to contain animal parts not only aren't what they're advertised to be, they're actually dangerous, he says. "We've found out that the great majority of medicines from China that claim to contain rhino horn or tiger bone or other endangered species parts in fact do not. But they often contain very high levels of arsenic and mercury — enough to be lethal to humans."

And sometimes the lab finds that even though the victim is in fact a protected species, its death wasn't a crime — because some perpetrators are outside the law. "When you have a protected animal that is dead, normally the first inference we make is that somebody killed it, but sometimes after doing a necropsy, we find that in reality the trauma is due to interpredator rivalry or fighting," Espinoza says. "And in that case, it's not an illegal act, because it's being committed by other animals."

More on