Forensics Project Part II: Hair and Fiber Analysis

1.  History of Hair/fiber analysis

Investigators recognized the importance of analysis of hair as trace evidence in criminal investigations in the late 1800s. The case of the murder of the Duchesse de Praeslin in Paris in 1847 is said to have involved the investigation

of hairs found at the scene.

A classic 1883 text on forensic science, The Principles and Practice of Medical Jurisprudence by Alfred Swaine Taylor and Thomas Stevenson, contains a chapter on using hair in forensic investigations. It includes drawings

of human hairs under magnification. The various parts of human hair are identified. The book also references cases in which hair was used as evidence

in England.

In 1910, a comprehensive study of hair titled The Hair of Man and Animals was published by the French forensic scientists Victor Balthazard and Marcelle Lambert. This text includes

numerous microscopic studies of hairs from most animals.

The use of the comparison microscope to perform side-by-side analysis of hairs collected from a crime scene and hairs from a suspect or victim first occurred in 1934 by Dr. Sydney Smith. This method of comparison helped solve the murder of an eight-year-old girl.

Further advances in hair analysis continued throughout the 20th century as technological advances allowed for comparison of hairs through chemical methods. Today, hair analysis includes neutron activation analysis and DNA fingerprinting and is considered a standard tool in trace evidence analysis.

2. Picture and labeled parts of a complete hair

3. Major types of fibers (other than hairs), for instance, polyester, cotton, etc.  Include at least 5 fibers

a. Cotton: soft fiber that grows around the seeds of a cotton plant and is one of the most commonly used fibers in clothing.

 b. Polyester: a strong fiber that is resistant to crease, stretching and shrinkage, hence the ability to hold its shape well

c. Silk: a protein fiber made from silk worms. Used in clothing for its smooth quality, color retention, and strength although it can be weakened by sweat, deodorant, and sunlight.

d. Linen: Linen is a plant fiber made from the stalk of the flax plant and like cotton takes to dyes easily and can be boiled without damaging the fiber. Fabrics made from linen are comfortable, highly absorbent, and has a natural luster and crisp hand. Linen wrinkles easily but also presses easily. It has poor elasticity and does not spring back readily like wool.

   

 e. Rayon: a man-made fiber but is not considered a synthetic fiber, but a manufactured regenerated cellulosic fiber. It can imitate the feel and texture of silk, wool cotton and linen. Rayon is highly absorbent but does not insulate body heat, hence making rayon garments ideal for use in hot and humid climates.

4. Hair/Fiber collection techniques

a. Hair can be collected by using tape or tweezers and place in paper bindles or coin envelopes which should then be folded and sealed in larger envelopes. Label the outer sealed envelope. If hair is attached, such as in dry blood, or caught in metal or a crack of glass, do not attempt to remove it but rather leave hair intact on the object. If the object is small, mark it, wrap it, and seal it in an envelope. If the object is large, wrap the area containing the hair in paper to prevent loss of hairs during shipment.

 b. If threads or large fibers are found, they can often be picked up with the fingers or tape and placed in a paper bindle, then in a coin envelope, which can be sealed and marked. Never place loose fibers directly into a mailing envelope since they can be lost from this type of envelope.

5. Typical Hair/fiber analysis.  How do scientists analyze and use hair/fiber data.

At a crime scene hairs and fibers can be collected to give detectives and forensic analysts clues to try to identity a suspect. If a hair sample still has skin tissue then it can be run for DNA but if not the hair can be looked at under a microscope and give a general group of people that the suspect of victim could have fit. A hair sample can show what gender and race the person was. Also about one hundred hairs fall from a person’s head each day and if someone’s hair is found at the crime scene or somewhere where the body was that is something that can link someone to that place. The same thing goes fibers from clothing. If fibers are found at the crime scene they can be matched to a suspects clothing and link them to the scene.

Types of Hairs:

In class we were provided with ten hair/fiber samples and we had to observe each sample under a microscope. We then had to identify the color, condition of tip, any observable spots or distinguishing features as well as drawing a diagram of each hari/fiber strand we saw.

6. Reliability of Hair/fiber crime scene data

Although some people have been convicted or exonerated based on hair and fiber evidence the extent to which the information it can supply is limited. Hair samples are good for narrowing down a general group of characteristics for a suspect but unless the root of the hair has skin tissue still on it, the suspect cannot be specifically identified.

7. Research any notable or famous case where hair/fibers were used to convict or exonerate a suspect.

In 1958, the body of 16-year-old Gaetane

Bouchard was discovered in a gravel pit near her home in Edmundston, New Brunswick, across the Canadian/U.S. border from Maine. Numerous stab wounds were found on her body. Witnesses reported seeing Bouchard with her boyfriend John Vollman prior to her disappearance. Circumstantial evidence also linked Vollman with Bouchard. Paint flakes from the place where the couple had been seen together were found in Vollman’s car. Lipstick that matched the color of Bouchard’s lipstick was found on candy in Vollman’s glove compartment. At Bouchard’s autopsy, several strands of hair were found in her hand. This hair was tested using a process known as neutron activation analysis (NAA). NAA tests for the presence and concentration of various elements in a sample. In this case, NAA showed that the hair in Bouchard’s hand contained a ratio of sulfur to phosphorus that was much closer to Vollman’s hair than her own. At the trial, Vollman confessed to the murder in light of the hair analysis results. This was the first time NAA hair analysis was used to convict a criminal.