How to Identify Minutiae in Fingerprints

A hand magnifier can help the fingerprint examiner locate minutiae points by enlarging the viewing area.

Fingerprints can be classified as one of three basic patterns: loop, arch and whorl. These patterns are characterized by the appearance of the ridges that compose the print. Minutiae points -- the beginning, end or branching off of a ridge -- are used to determine whether two fingerprints come from the same source. Locating and comparing these minutiae points occurs after a fingerprint examiner has confirmed that both fingerprints have the same pattern type and general ridge flow.

Things You'll Need

• Fingerprint magnifier

Instructions

1. Enlarge the viewing area of the fingerprint with a magnifier. This can be accomplished with a standard magnifying glass or a fingerprint magnifier, which is a hands-free magnifier attached to a base.

2. 

   The ridges of this fingerprint are shown in black. Minutiae points are located within these black ridges.

   Locate minutiae points within the ridges of the fingerprint. Minutiae points can be found in the form of bifurcations, ridge endings or dots. A bifurcation is the point at which a single ridge splits into two ridges. A ridge ending is the abrupt ending of a ridge. A dot, also known as an island or short ridge, is a ridge so short that it appears elliptical or circular.

3. Record the minutiae point locations by pressing into the surface with a sharp pointer or by using an ultra fine-point marker. Marking these points allows the examiner to move on to different areas of the print without having to remember the location of previous minutiae points. This is also helpful when comparing the marked minutiae points of two fingerprints for identification purposes.

Tips & Warnings

• In case work, do not mark on the original fingerprint. Mark on a high-resolution copy. Most fingerprint examiners prefer to work on slanted desks to put less stress on their back. Fingerprint examination can be a time-consuming process, so work at your preferred comfort level. Sufficient lighting is also essential.

References

• "Forensic Science: An Introduction to Scientific and Investigative Techniques"; Stuart H. James, et al.; 2009
• Biometrics.gov: Fingerprint Recognition