Sweat contains a rich array of chemicals and there is plenty of it. A typical person has, per square inch of skin, some 650 sweat glands. The net effect is that our bodies deposit small amounts of sweat on everything that is touched. This means mundane activities like making a phone call or eating meal. And, of relevance to the new research, committing a crime.
The ubiquity of sweat deposits lead Jan Halámek to contend that investigators can use these skin secretions to their advantage. Working at the University at Albany, Halámek undetook research that proposes that analyzing sweat left behind at a crime scene can be used to determine the number of people who were there. Such analysis can be used on site at the scene and offer immediate results.
The basis of the research is centered on sweat containing a large number of amino acids and metabolites. Halámek has shown how these biochemicals can be targeted once detected on a surface. The research focused on three metabolites: lactate, urea and glutamate. Here, lactate appears in high concentrations of sweat and varies greatly based on a person’s lifestyle. Additionally, Urea and glutamate, also highly concentrated, are found in different parts of our sweat. The chances of two people having the same levels of all three metabolites is virtually zero.
These findings have been reported to the journal Analytical Chemistry. The research paper is headed “Metabolite Biometrics for the Differentiation of Individuals.”
In statement, Halámek explains the research background in a communication to Digital Journal: “We are looking at two concepts in this paper. First, that each of our skin secretions are different and, therefore, unique to us. Like a fingerprint. Also, we are continuously secreting sweat throughout the day that is being deposited in small amounts as we travel and touch various objects.”
He explains further: “By combining these concepts, we were able to show that, statistically, sweat left behind at a crime scene can help forensic investigators.”
The next step is to test out the analysis on real crime scene samples.
