Why Are Fingerprints Unique?

Why Are Fingerprints Unique?

Every investigation is unique, no two are ever the same and they’re a full of twists and turns – and so is this blog’s topic: a brief look at fingerprints.

The skin on the underside of our hands and feet are covered with indentations known as papillary ridges. These ridges form the patterns that make our completely unique fingerprints. Fingerprints are an evolutionary quirk; often thought to help us grip surfaces, but have since become an identification method.

For biometrics and forensics, fingerprints are read in a series of minutiae which are made up of: ridge endings, ridge bifurcation (a single ridge that divides into two ridges), short ridges, islands (a ridge inside a short ridge or ridge ending that is not connected to all other ridges), ridge enclosures (a single ridge that bifurcates and reunites shortly afterward to continue as a single ridge), spurs (a bifurcation with a short ridge branching off a longer ridge), bridges (a short ridge that runs between two parallel ridges), a Y-shaped ridge called a delta, and a U-shaped ridge called a core.

These points and the lines that connect them make a unique pattern, completely bespoke for each person. It is statistically impossible for two fingerprints to be alike, which makes them ideal as an identity marker.

Biometrics is the term given for body measurements used for authentication. Biometrics are exponentially more secure than usernames and passwords, but there are some ways in which these can be faked. By using glue, putty, tape or several other bodges, you can make a negative of a fingerprint and use it to trick fingerprint scanners.

Some people go to some extreme length to protect their identity and have actually had their fingerprints altered and removed. One of the most common ways to change your fingerprints is to add some substantial scarring to the area. This alters the ridges and creates a different texture to any that might be on record. This, of course, only changes the fingerprint rather than removing it, and would be a significantly painful procedure.  Removing them entirely is not an effective solution for masking identity, whereby the skin is grafted from a smooth area of the body.

Altering or removing fingerprints can be classed as obstruction of justice, so ultimately, is a complete waste of time and money.

Fingerprints can be a fantastic tool during an investigation as they’re a simple way to identify a person from a crime scene, but for a direct and thorough investigation, sometimes fingerprinting can just add more confusion. Simple being in a room where a crime took place, is not enough to prove any guilt… but I’m not above grabbing a blusher, a brush and some Sellotape for some makeshift dusting.