Finding a person’s fingerprints at a crime scene isn’t always enough to convict them, as they can claim that those prints were left before the crime took place. That may be about to change, though, as scientists have now devised a method of dating fingerprints

Led by Assoc. Prof. Young Jin Lee, a team from Iowa State University recently decided to investigate an existing theory – it suggests that as a fingerprint ages, ozone in the surrounding air reacts with unsaturated triacylglycerols deposited by the fingertip.

The scientists studied multiple prints from three volunteers, which were left on various surfaces over a period of seven days. Utilizing a technique known as mass spectrometry imaging, the researchers were able to reliably determine when each print was left, based on the rate at which its triacylglycerols had degraded.

The examination process didn’t harm the fingerprints, so they could still be used for identifying individuals. Additionally, the prints could still be dated even after having been dusted with forensic powder.

It was noted that the rate of degradation varied considerably from person to person, likely because of the differing amounts of lipids in their fingerprints. This means that a print couldn’t be dated until police knew who it was from, and had established that person’s unique triacylglycerol profile.

A paper on the research was published this week in the journal Analytical Chemistry.

https://newatlas.com/science/fingerprint-dating/

> The scientists studied multiple prints from three volunteers, which were left on various surfaces over a period of seven days. Utilizing a technique known as mass spectrometry imaging, the researchers were able to reliably determine when each print was left, based on the rate at which its triacylglycerols had degraded.

Nice.

> The examination process didn’t harm the fingerprints, so they could still be used for identifying individuals. Additionally, the prints could still be dated even after having been dusted with forensic powder.

Extra nice.

I’ve heard that some children don’t leave fingerprints, they evaporate fast leaving very little residue, but this technique would be sensitive enough to pick them up.

> mass spectrometry imaging

This exists? According to wiki it does. https://en.wikipedia.org/wiki/Mass_spectrometry_imaging . There are three types and the type used here would be DESI.

“Desorption ElectroSpray Ionization is a less destructive technique, which couples simplicity and rapid analysis of the sample. The sample is sprayed with an electrically charged solvent mist at an angle that causes the ionization and desorption of various molecular species. Then, two-dimensional maps of the abundance of the selected ions in the surface of the sample in relation with the spatial distribution are generated. This technique is applicable to solid, liquid, frozen and gaseous samples. Moreover, DESI allows analyzing a wide range of organic and biological compounds, as animal and plant tissues and cell culture samples, without complex sample preparation. Although, this technique has the poorest resolution among other, it can create high-quality image from a large area scan.”