Using Smell to Solve Crime

Scientists believe body odor lineups might assist in solving crimes. AP

Scientists already know scent is a strong trigger for memories—more so than any other sense. Now, in a new study, researchers are hoping to put our smart noses to use in helping victims of violent crimes identify the culprits.

Everyone who has ever seen a cop drama is familiar with the eyewitness lineup: Victims, relying on visual memories, try to pick out the suspect from a group of randomly chosen strangers. But in recent years, more and more data have come out suggesting that eyewitnesses show a decreased accuracy in recognizing perpetrators visually, perhaps due to the trauma associated with a frightening event. So forensic scientists have been looking for new ways to help victims identify their perps.

A group of researchers from University of Aveiro in Portugal decided to test scent. The team showed videos of violent crimes to 40 student participants while asking them to take a whiff of a body odor sample taken from the armpits of a donor. Afterward, the students were given five different smelly glass jars and asked to try to ID the B.O. they had sniffed earlier.

They were successful 75 percent of the time—a significant increase from the 45 to 60 percent accuracy rate of the eyewitness lineup. It's not clear why smell made such a difference in the experiment, although the researchers believe it might have to do with negative emotions experienced at the same time as the encoding of the body odor.

Larry Kobilinsky, professor and chairman of forensic science at John Jay College, who was not involved in the study, believes researchers will have a hard time getting this technique into the courtroom. Odor is complex, he explains, and can change from day to day: there are too many variables that weren't accounted for in the study. "I'm not convinced that it's ever going to be found admissible," he says. "How many false positives and false negatives are this technique going to produce? In forensics you're dealing with real life, and just think about the variation that might occur in odor over the course of a single day, let alone a week or a month [until the criminal is caught]."

The researchers point out that "every individual has a unique body odor, similar to a fingerprint," and they did try to control for variation: Before taking body odor samples, they asked the volunteer donors to not wear any deodorant, cologne or partake in any activities that might change their natural smell. But in real life, of course, you can't exactly ask a criminal to go easy on the aftershave.