Suspects' Gender Determined at Crime Scene


By Mona Simpson

When a crime has been committed, investigators need clues quickly to identify suspects from what might be a long list. Fingerprints let them know who touched objects at a crime scene, but those prints can help identify people whose prints are already in a database. DNA can identify people using the tissues found at the crime scene, but that process requires time and an equipped laboratory.

A New Tool

Now biomarkers can let investigators quickly test evidence to determine the gender of a crime suspect at the scene of the crime using colorimetric assay.

Colorimetry measures color. A colorimetric assay measures the color of a sample against known colors. The sample may be colored already or it can be colored through a reaction. If we know that the intensity of color (absorbance) is proportional to the concentration of the substance being tested, then a colorimeter or spectrophotometer can find the concentration of the solute.

It is known that men and women vary slightly in their blood levels of creatine kinase (CK) and alanine transaminase (ALT). Evgeny Katz at Clarkson University, Potsdam, and Jan Halamek at the University at Albany, State University of New York, amplified the difference between male and female samples using a series of chemical reactions, until the final step uses a colored compound to allow the gender to be determined visually. The levels of these biomarkers, just like all biomarkers, can give unexpected results in ill or diseased individuals, in which case gender may be unable to be determined. But this extra amount of information gives investigators an edge in pursuing the right suspect.

Currently, this technology has been developed for lab use, but efforts are being made to make this test field-ready. This test is not nearly as specific as DNA analysis, but its simplicity and the swiftness of results may make it immediately useful to determine the gender of criminals at the crime scene.

Classroom Discussion

  • How would determining the gender of a crime suspect help investigators?