chapter 14: fingerprints “fingerprints can not lie, but liars can make fingerprints.” —unknown

Chapter 14:Chapter 14: FingerprintsFingerprints

“Fingerprints can not lie, but liars can make fingerprints.”

—Unknown

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SkinSkin

Outer Layer

Inner Layer:Contains sweat glands

Boundary betweenContains friction ridge structures

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FingerprintsFingerprints

Sweat gland ducts extend up through the epidermis where theyrelease perspiration, oils, and salts. These leave an identifiableresidue conforming to the pattern of an individual’s fingerprints.

Papillae form during fetal stage of development and remainunchaged during life.

No two prints are alike,even for identical twins.

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3 types of fingerprints3 types of fingerprints

Visible prints - prints that are visible due to the background or surface they are on.

Plastic prints - those that are made by an impression on a material

latent prints - invisible prints that need to be made visible by mechanical or chemical means

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Fundamental PrinciplesFundamental Principlesof Fingerprintsof Fingerprints

A fingerprint is an individual

characteristic.

A fingerprint will remain unchanged

during an individual’s lifetime.

Fingerprints have general characteristic

ridge patterns that permit them to be

systematically classified.

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LoopLoop

A loop must have one or more ridges entering and exiting from the same side. Loops must have one delta.

What are the 2 bones in the forearm?

Types Radial—opens toward the

thumb Ulnar—opens toward the

“pinky” (little finger) Which type of loop is this, if it is

on the right hand? Left hand?

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WhorlWhorl

Whorls have at least two deltas and a core.

3 Types Plain or Central Pocket Whorl

has at least one ridge that makes a complete circuit.

Double Loop Whorl is made of two loops.

Accidental Whorl is a pattern not covered by other categories.

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ArchArch

An arch has friction ridges that enter on one side of the finger and cross to the other side while rising upward in the middle. They do NOT have type lines, deltas, or cores.

Types Plain Tented - has a spike in

the center- looks like it’s holding up a tent

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John DillingerJohn Dillinger

Tried to remove fingerprints with acid Partially successful, but enough remained

for identification.

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Other PrintsOther Prints

Ears—shape, length and width

Voice—electronic pulses measured on a

spectrograph

Foot—size of foot and toes; friction ridges on the foot

Shoes—can be compared and identified by type of

shoe, brand, size, year of purchase, and wear pattern.

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Other PrintsOther Prints

Palm—friction ridges can be identified and may be used against suspects.

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Other PrintsOther Prints

Footprints are taken at birth as a means of identification of infants.

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Other PrintsOther Prints

Lips—display several common patterns

Short vertical lines Short horizontal lines Crosshatching Branching grooves

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Other PrintsOther Prints

Teeth—bite marks are unique and can be used to identify suspects. These imprints were placed in gum and could be matched to crime scene evidence.

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Other PrintsOther Prints

The blood vessel patterns in the eye may be unique to individuals. They are used today for various security purposes.