A new technique for decoding the smell of a person’s hand could be used to help forensic investigators catch criminals. Testing out their method on 60 volunteers, a team of scientists successfully identified the sex of more than 96 percent of participants, revealing how the approach may help to narrow down the identity of felons.
“Criminal activities involving robberies, assaults (sexual, simple, or aggravated), and rape are often executed with the use of the perpetrator’s hands,” write the researchers in a new study. “As a result, hands are a focal point of investigations as contributors of trace amounts of evidence that can be deposited on everyday objects through touch interactions,” they continue.
Typically, detectives look for giveaways such as fingerprints or DNA left behind by a sloppy lawbreaker’s mitts, although in many cases, such telltales are absent from a crime scene. However, the study authors insist that “even in these instances where no physical fingerprint or DNA evidence is found, human scent evidence may still be recovered and used as an individualizing feature in an investigation.”
To devise a means of capturing and utilizing hand smell, the researchers analyzed the volatile scent compounds on the palms of 30 men and 30 women, all of whom were instructed not to wash their hands for one hour prior to having their samples taken. They then performed a statistical analysis to see if these odors could be reliably classified as either male or female.
Overall, they were correctly able to identify the sex of 58 of the 60 participants based on the smelly chemicals emitted by their hands. This equates to a 96.67 percent success rate - an achievement which the authors say “could aid investigations to eliminate 50% of the population from subsequent considerations.”
“The overall impact of this study could assist in changing the trajectory of how we currently utilize human odor in the field of forensic,” they write.
Given that previous research has indicated how odor can be used to identify a person’s age and racial or ethnic group, the advent of a technique to discern sex suddenly opens up new possibilities for honing in on a suspect based on the volatile compounds found at a crime scene.
Summing up the significance of their work in a statement, the researchers state that “this approach to analyzing hand odor volatiles can be applied when other discriminatory evidence such as DNA is lacking and allow for differentiation or class characterization such as sex, race and age.”
The study is published in the journal PLOS ONE.