Hair/Fiber Analysis

History

An important part of forensic science is the anlysis of hairs and fibers found on the crime scene. When a crime is committed, the perpetrator will nearly always leave some trace in the form of a hair or fiber from clothing. Even if there is no trace of the perpetrator, fibers from the victim can also be an important clue to who committed the crime and how it occurred. Analysis of hair and fibers has played a key role in many investigations since it first became used widely in the 20th century. The first crime solved by hair analysis occurred in 1899, when a hair that was foudn to be dyed linked a suspect to the crime. Another case in which this analysis was critical was the Atlanta Child Murders. In this case, at least 28 African-American residents of Atlanta,Ga were killed by Wayne Williams. Police staked out a river where he had been dumping bodies, and followed his car. They pulled him over and recovered dog hairs and other fibers that they would later use to convict him of the murders. He was sentenced to two consecutive lifetimes in prison.

Use of Fibers in Investigations

Fibers can link a suspect to a victim when a certain fiber is found on both the victim and the suspect. Fibers can easily be transferred from one person to another though physical contact. There are several considerations that investigators use to determine if there is a link between a victim and a suspect of item. These include

• Type of Fiber
• Fiber Color
• Location of Fiber
• Number of Fiber Associations

Using this criteria, the investigators can determine if there is a strong link between the fibers found on the crime scene and in other locations. These can also give clues to how a crime was committed. For example, if many similar fibers are found on both a victim and a suspect, it could indicate that there was significant violent physical contact between the victim and the criminal/
Hair/Fiber Analysis Lab
We conducted a study of various hairs and fibers by viewing them under a microscope and drawing the fiber in detail. Every fiber and hair was unique, and we learned to distinguish between hair of different races and genders.

Examples of Types of Fibers:


Nylon:

Silk:

Fingerprint Patterns

Fingerprint Patterns

Fingerprints are differentiated by the patterns that are formed in the print. There are three main types of patterns found on fingerprints.

The most common type of fingerprint pattern is the loop. Around 60-70 percent of fingers have this pattern. Loops are broken down into two categories: radial loops and ulnar loops. Radial loops angle towards the thumb, and ulnar loops angle towards the little finger.



The second most common fingerprint pattern is the whorl. Whorls can be identified as one of four types: Plain Whorl, Central Pocket Loop, Accidental Whorl, and Double Loop. Whorls are formed from at least two deltas, and the categories listed are based on loops found in the pattern how the loops relate to the delta patterns.



 The third and final type of fingerprint pattern is the arch. Only 5 percent of fingers have this pattern. Arches fall into one of two categories: Plain Arch and Tented Arch. Tented arches have an upthrust or upward angle that has a sharp peak. Plain arches do not have this sharp angle.


Identifying Fingerprint Patterns

Using blue ink and the paper shown above, we gathered the fingerprint for each of our fingers and identified them using the above classifications. My thumbs were radial loops, and my other fingers all had central pocket loops.

Types of Fingerprints

When fingerprints are collected for a crime scene, they are not always easily accessible and visible. There are three basic types of fingerprints, categorized by the way they are left on the scene and the way they are collected.

Visible/Patent Prints: a physical print on a surface in a substance such as blood that allows the fingerprints to be easily visible to the naked eye.

Latent Prints: not visible to the naked eye; formed from sweat; must be developed before they can be viewed or photographed. They can be made visible by dusting, fuming, or chemical reagents.

Impressed/Plastic Prints: indentations left in soft pliable surfaces, such as clay, wax, paint or another surface that will take the impression. They can be viewed or photographed with the naked eye

A Timeline of the History of Fingerprinting

TIMELINE OF FINGERPRINTING
1686: Marcello Malpighi first noted ridges, spirals, and loops in fingerprints
1858: Handprints are used by English-controlled India to be imprinted on contracts to make the contract more binding than just a signature. The handprints were not used for identification
1880: Dr. Henry Faulds discussed for the first time the use of fingerprints as a means of personal identification
1882: Gilbert Thompson applied his fingerprint to a document to avoid forgery
1883: A fictional murderer in Mark Twain’s “Life on the Mississippi” is identified using fingerprint identification
1892: First criminal fingerprint identification takes place. Juan Vucetich identified Francis Rojas as the murderer of her two sons and herself after her bloody fingerprints were found on a door post
1903: First systematic use of fingerprints for criminal identification occurs in New York
1905: First use of fingerprints by the US Army
1946: Automatic fingerprint identification technlogy is developed