New analysis method: is a fingerprint an impression in blood or made by blood?

Fingerprint experts of the Netherlands Forensic Institute (NFI) have developed a new method to determine the order in which blood and a fingerprint ended up on an object.

The method mainly focuses on verifying tactical evidence, such as statements made, and has been used in the Netherlands in a couple of cases investigated by the police.

Whether a bloody fingerprint was left in or with blood, can tell us something about the order of events leading up to a crime. The NFI has carried out tests with lots of different materials on which blood is commonly found, including porcelain, wood, steel, cardboard and paper. The method appears to work best on somewhat firmer surfaces.

The two types of fingerprint show differences in terms of their appearance. Some characteristics can be observed with the naked eye, some can only be seen with sensitive cameras and microscopes and some need specific spectroscopic methods.

Verification of statements

The new method is not specifically meant to quickly identify a suspect. “To find out whose fingermark was left at the crime scene, the police can resort to existing methods in the field of fingerprint technology. The findings of those analyses prompt another question: how did the fingermark get there? It is this new method that provides more information on the activities leading up to the deposition of the mark”, researcher Marcel de Puit says.

Hundreds of tests

For this method, the NFI performed hundreds of tests. In more than 80% of the cases, fingerprints leaving an impression in blood, show a distinctive circle around the fingerprint. Regardless of the amount of blood, none of the fingerprints made by blood, showed such a circle.