With today’s technology, determining the individual who left behind a fingerprint can be as easy as scanning the fingerprint in question into a computer and finding a match. AFIS stands for the Automated Fingerprint Identification System  and works by comparing an unknown fingerprint to those of 70 million known criminals. If a person who was previously convicted of a crime commits another offense and leaves behind a fingerprint, even just a partial print, AFIS would be able to match that print with their prints already in the system. Although analyzing fingerprints seems like a simple task, they are actually very complex pieces of evidence.

To start, there are three main types of fingerprint patterns, Loops, Whorls, and Arches. Loops are the most common of the three and make up about 70% of all fingerprints. Loops flow in on one side of the finger, loop around, and exit on the same side of the finger that the patter entered on. Loops contain only one delta. A delta is when the ridges of the fingerprint pattern form together to make a triangle shape. There are two subcategories of loops known as ulnar loops and radial loops. If the loop pattern flows in from the thumb side than it is a radial loop while if it flows in from the pinky side than it is an ulnar loop. The second most common fingerprint pattern is the whorl. A whorl pattern consists of a series of circles inside each other. Whorls contain two deltas and there are four subcategories. Plain whorls make a complete circuit where you are able to draw an imaginary line between the two deltas that touches a whorl ridge. A central pocket loop whorl is similar to a plain whorl except if you draw an imaginary line between the two deltas it will not touch a whorl ridge. Double loop whorls occurs when two loops are formed to make a whorl. Any whorl that does not fit the description of the first three types is known as an accidental whorl.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The least common of three fingerprint patters are called arches. The ridges of arch fingerprints enter from one side of the finger and exit through the other and contain no deltas. There are two types of arches; plain arches and tented arches. Plain arches have a wave like pattern while tented arches show a sharp spike at the center of the arch.

 

 

 

 

 

 

 

 

Since there are only three main types of fingerprint patters, it’s the minutiae of each individual fingerprint that makes each one unique. Each ridge ending, dot, lake, bridge, bifurcation, etc. of each fingerprint is unique to that fingerprint only. Just imagine, back in the day, fingerprint experts had to sit and make note of every single little characteristic of each fingerprint in order to get an accurate comparison.

No two fingerprints are exactly the same, even for identical twins. Each person could have all of one of the pattern types on each finger or a mix of all three. Luckily, technology has allowed us to easily match unknown fingerprints left behind at crime scenes to those of many known criminals. Fingerprint evidence is an extremely useful tool and is one of the most important ways we are able to connect criminals to the crimes they have committed.