New Possibilities for Reporting Fingermark Evidence
With a new method developed by the Netherlands Forensic Institute (NFI), it is now possible to report the evidential value of fingermarks containing less than 12 dactyloscopic features. In the Netherlands, the results of this method have already contributed to convictions in a number of cases.
When a fingermark is left on a crime scene, there is always a certain loss in quality compared to the original fingerprint: quantitatively, due to the limited size of the fingermark, and qualitatively, due to fading, damage, and distortion. This makes it difficult to compare fingermarks with reference fingerprints.
Until recently, the forensic standard used for comparison in the Netherlands prescribed that there had to be at least 12 dactyloscopic points (features of fingerprints) of agreement between a questioned fingermark and a reference fingerprint in order to report an identification. The result of the examination is reported in three ways, i.e. identification, exclusion or inconclusive, in other words: the fingermark and fingerprint are from the same finger, from different fingers, or are of insufficient quality to make such a statement. As a consequence, a lot of high quality fingermarks containing less than 12 features remain unreported to the judicial system.
With the new method developed by the NFI, the evidential strength of a comparison of a fingermark and a reference fingerprint is measured using a statistical evaluation. This new type of evaluating fingermark evidence enables the NFI experts to report on fingermarks with less than 12 features. By using a scientific method for the comparison of a fingermark and a fingerprint, it is now possible to calculate the evidential strength (likelihood ratio) of the comparison. Fingermarks that were not considered in the past can therefore now be examined and used as evidence in the courtroom.