An examiner must be able not only to recognize what type of print a particular sample is or what category it fits into but also to identify, or match, at least 12 points. Fingerprint matching techniques can be placed into two categories: minutiae based and correlation based. Minutiae-based techniques first find minutiae points and then map their relative placement on the finger. However, there are some difficulties when using this approach. It is difficult to extract the minutiae points accurately when the fingerprint is of low quality. Also this method does not take into account the pattern of ridges and furrows.
The correlation-based method is able to overcome some of the difficulties of the minutiae-based approach; however, it has its own shortcomings. Correlation-based techniques require the precise location of a registration point and are affected by image translation and rotation (that is, the moving of one print relative to the one being compared).
Another problem that examiners must overcome is print size. Because there is no standard requirement of print size for positive identification, the print need only be large enough to contain the necessary points of individuality. Therefore, if the examiner can determine the "necessary" number of points, the print will suffice.
The fundamental benefits of fingerprint identification are permanence and individuality. It is these two characteristics that make the science of fingerprinting appropriate for individual identification and, thus, an excellent source of evidence for law enforcement.
© Infobase Publishing
When developed and processed correctly, fingerprints have obtained convictions on numerous cases. In the roughly 100 years that fingerprints have been used for identification purposes, no one has managed to falsify the claim of uniqueness by showing that fingers of two persons had identical fingerprints. Furthermore, other than growth and scarring, no one has shown that the distinctive characteristics of one person's fingerprints changed over time. This is why fingerprint examination, or dactylography, is such a reliable science.
Was this article helpful?