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forensic science part 5: fingerprinting

i actually love fingerprinting people. i just love the whole process and i think it's super interesting to be able to figure out what kind people have.


there are three distinct types of fingerprints: loops, whorls, and arches. each of them have subcategories as well.

loops: a loop is a type of fingerprint where long, raised lines (or friction ridges) emerge from one side of the print, curve upwards, loop around, and exit on the other side of the print. 
ulnar loops: an ulnar loop is when the top of the loop points toward the ulna, one of the bones in the pinky. 
radial loop: a radial loop occurs when the top of the loop points toward the radius, which is  a bone near the thumb. 
not all loops look the same; not even every radial loop on the pointer finger looks the same. your two hands are mirrored, so if you hold them palm up right next to each other, your pinkies will be on opposite sides of the hand. because of this, an ulnar loop on your right hand will point to the left, whereas an ulnar loop on the left hand points to the right. it is important to determine which hand your fingerprint came from, not just for record keeping purposes, but also because they are labeled differently for each hand.
something to remember about loops is that they only have one delta. a delta is a spot in a fingerprint where lines converge to form a triangle shape. this usually occurs at the bottom of the fingerprint.
loop fingerprints make up 65% of all fingerprints. they are the most common type of fingerprint. 

whorls: a whorl is a fingerprint pattern where the friction ridges form a complete circle near the middle of the fingerprint.
double loop whorl: a double loop whorl is a type of whorl that is made up of two loops originating from opposite sides of the fingerprint 
it is important to note that both types of whorls have two deltas, one on each side of the whorl itself. double loop whorls are less common than simple whorls, but they can be found in approximately 25-35% of all fingerprints. 
when typing whorls it is not as important to know what hand it came from to be able to know what exactly it is. whorls do not point in a specific direction, they just form circles.

arches: an arch is a type of fingerprint in which friction ridges emerge from one side of the finger, curve up slightly, then comes back down and exits through the other side of the finger. 
tented arch: a tented arch occurs when two independent friction ridges come together to form an angle
arches are the most uncommon form of fingerprint. only approximately 5% of the population have arches as fingerprints. those who have one arch are more likely to have more than one. again, it is not important to know which hand the fingerprints came from in order to type it correctly. an arch does not point in any specific direction. 
arches usually do not have deltas, however tented arches may have a delta in the center of the arch. this is because they are made up of two independent ridges that meet each other near the middle.

here is a chart of the different types of fingerprints. 
keep in mind that a left loop could be ulnar or radial depending on which hand it is located on; the same can be said about a right loop.

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