Hair/Fiber Collection Techniques and Analysis

The Crime Scene

During collection of fibers at a crime scene, fibers need only be placed in individual envelopes and marked as evidence. The same holds true for hairs, but if a hair is attached to another object certain steps have to be taken. If the object on which the hair is attached is small, such as a shard of glass, the hair and object must be placed in an evidence envelope and marked. If the object is too large, the are around the hair must be wrapped in paper to prevent loss of hair evidence. Tweezers can be used for removal of hairs or fibers if necessary.

Analysis

Both hairs and fibers are analyzed using microscopy technology to compare samples, but the actual analysis varies between hair and fiber samples.

Hair

Individual strands of human hair, through analysis, can determine the race and relative age of the person from which the sample came as well as from where on the body the hair was located. In addition, dyed hairs are easily discernible under a microscope and can help identify the owner. Analysis of hair roots can determine how the hair was lost from the body. These traits discovered through hair analysis can help narrow the search scope and ultimately lead to the identification of a suspect. DNA can also be extracted from strands of hair to positively identify the perpetrator, instead of just narrowing the search.

Fiber

In contrast, fiber evidence is analyzed to associate a suspect through statistical elimination. Fibers found at the crime scene must be compared to fibers linked to a suspect. Moreover, the fiber has to be proven to be unique and therefore establish odds that the sample collected came from the suspected source. For instance, in the Atlanta Child Murder case, statistical evidence was used to determine that the chance the samples collected belonged to anyone other than the suspect was 1 in 29,827,776.

Reliability

Hair and fiber evidence is usually able to help establish a significant lead in a criminal case, but results based solely off such evidence is rarely considered conclusive. Statistical elimination is helpful in minimizing a list of suspects but ultimately can't be used as conviction-worthy evidence. Only DNA extracted from a hair sample is considered reliable and conclusive.

Major Types of Fibers

Cotton
Cotton is the most commonly used plant fiber in production, with almost all clothing containing some amount of manufactured cotton. The type, length, and color of the identified cotton fibers are significant in narrowing the search to one textile producer. From there, the rarity of the fiber can be considered and statistics can determine the odds in which the cotton found at the crime scene belonged to a suspect.


Wool
Wool from sheep is the most common animal fiber found at a crime scene. The coarseness of the wool is a large factor in determining the origin of the fiber. Fine wool is used for clothing while the coarser strands of wool are used in carpet production. Other wool fibers from less common sources (such as a camel) can drastically increase the rarity of such fibers and therefore minimize statistical odds.



Nylon
Nylon is a very common synthetic fiber first used as a replacement for silk. Because of the wide range of uses for nylon (carpeting, musical instruments, clothing, and rope) the ability to identify a rare source is somewhat reduced. However, rope fibers at a crime scene are often matched to a suspect's rope in murder or kidnapping cases. The color and other properties of the nylon can help identify their use and therefore a source.

Silk
Silk is most often used for clothing made from extracted silkworm fibers (Bombyx mori). Silk isn't a very common fiber, which makes it easier to pinpoint a manufacturing source and determine the rarity of the substance. The chemical and physical properties of silk are very unique, as silk has an easily identifiable texture and is one of the strongest natural fibers in the world.





Linen
Linens are used in clothing and are valued for their ability to maintain their coolness in a hot climate. Linens are used to produce a variety of items like aprons, towels, bags, bed sheets, tablecloths, napkins, and clothing. The use of the sample can be determined by the length of the fiber. If the fiber is short, it is used for coarser fabrics, whereas longer fibers are used for fine fabrics. Since linens are an expensive textile, linen fabrics are produced in small quantities. This makes it a lot easier to find a source and a suspect because of the rarity of such material.

Hair/Fiber Famous Cases

Atlanta Child Murders

Between 1979 and 1981, 29 children were found strangled in the Atlanta area. On July 28, 1979, an investigation was launched in response to the "child murders." The only link between the killings was fiber evidence. Strands of unique yellow-green fibers were found on all of the bodies or their clothing. After media coverage of this discovery, the killer began dumping nude bodies in the river so as to minimize fiber evidence. On May 22, 1981, a police stakeout on a bridge over the Chattahoochee River heard a splash and stopped a nearby car driven by Wayne Williams. After questioning, Williams was allowed to leave. Two days later a body washed ashore downriver and a search warrant was obtained for Williams' house. Fibers similar to those found on all of the victims were found throughout Williams' house, although police had to prove that such fibers were rare in order for the discovery to be circumstantial. The odds that the fibers came from any place in Atlanta other than Williams' house were calculated to be about 1 in 7,792. In addition, different fibers were found on another victim's shorts which were similar to samples extracted from Williams' car. The combined odds that both fiber samples were from places other than Williams' house and car were 1 in 29,827,776, enough to convict Wayne Williams and sentence him to two life sentences in jail.

History of Handwriting Analysis

Handwriting analysis is incredibly important in identifying forgeries. Checks and other important documents that require signatures can easily be forged, but forensic handwriting analysts can judge their authenticity and therefore prevent criminals from getting away with their misdeed.

Handwriting analysis, sometimes called graphology, was first proposed in the 19th and 20th centuries by Abbe Jean Michon, Alfred Binet, and Milton Bunker. However, graphology has more to do with the relation of handwriting styles to psychology and the personality of the writer than actual forensic examination.

Forensic handwriting analysis wasn't actually used or introduced in criminal investigations until the beginning of the 20th century. Most notably, the kidnapping of Charles Lindbergh's baby in the 1930s marked the beginning of handwriting analysis in forensic investigations.

In 1993, the U.S. Supreme Court case Daubert v. Merell Dow Pharmaceuticals, while unrelated to handwriting analysis, set the precedent for evidence being submitted in court. The case established that expert testimony must be relevant and draw on generally accepted scientific method.

12 Handwriting Characteristics

Line Quality

Can determine the speed with which the sample was written by analyzing whether the letters are shaky or free flowing.

Spacing

Spacing of words and letters can help identify a forgery. The spacing can be consistent or inconsistent, which is an important factor in forensic handwriting analysis.

Ratio of Characters

This is the ratio of the width of letters to their height. If the document in question contains letters that don't have the same ratio as the actual writers', then the analyst can identify the document as a forgery.

Pen Lifts/Separations

Is the writing continuous or are there frequent pen lifts? If the lifts are unusual, a forgery is usually indicated.

Connecting Strokes

Sometimes capital letters are connected to lowercase letters, which is an easily identifiable handwriting trait.

Completion of Letters

Are letters complete? For example are "o"'s a complete circle or does the letter have a small opening?

Letter Formation

Letters can contain tails or small attributes. Capitals could be formed unusually, or letters can be backwards.

Pen Pressure

The pressure can either be placed on the up stroke or the down stroke.

Slant of Letters

Is the slant left, right, or straight? Are all letters consistently slanted?

Line Habits

Is the writing above, below, or on the line? Is the line consistent, or does it vary?

Embellishments

Some writing may contain flourishes in letters or curls at the tips.

Diacritic Placement

How are the letters crossed (t's and f's) and where on the letter is it crossed (high or low). Where are the dotted letters dotted. High? Low? To the right or left?

Handwriting Analysis Famous Cases

Kidnapping of Charles Lindbergh, Jr. 

On March 1, 1932, the son of the famous aviator Charles Lindbergh was kidnapped. A handwritten ransom note was left demanding a ransom of $50,000. After an extensive investigation and the discovery of Lindbergh, Jr.'s dead body, the police were led to a suspect named Bruno Richard Hauptmann. After searching Hauptmann's house, police found designs for a makeshift ladder similar to the one used to access the room in which the baby was kidnapped. In addition, the wood from the ladder was an exact match to a piece of wood found in Hauptmann's attic. This evidence led to the indictment of Bruno
Hauptmann.






Handwriting Experts
At trial, handwriting experts testified to point out the similarities between the handwriting on the ransom notes and Hauptmann's handwriting. The positive handwriting identification on the ransom notes was the nail in the coffin for Hauptmann. He was convicted of extortion and murder and sentenced to death. Hauptmann was electrocuted on April 3, 1936.

Works Cited

http://science.howstuffworks.com/fingerprinting3.htm

http://www.inspirationline.com/images/Fingerprinting1.jpg

http://galton.org/images/finger-prints.jpg

http://www.mseg.gba.gov.ar/PolCientifica2/fotos/rastros/grandes/lr_afis.jpg

http://www.bxscience.edu/publications/forensics/articles/fingerprinting/f-fing03.htm

http://thumbs.dreamstime.com/thumb_394/12412906444yw899.jpg

http://people.stu.ca/~mclaugh/PICS/FINGERPRINT.JPG

http://www.fingerprinting.com/fingerprint-patterns.php

http://www.brazoria-county.com/sheriff/id/fingerprints/tarch.jpg

http://www.pbs.org/race/images/loop_fingerprint.gif

http://www.creative-chemistry.org.uk/activities/images/prints/dloop.gif

http://www.odec.ca/projects/2004/fren4j0/public_html/fingerprint_patterns_files/image015.GIF

http://www.ehow.com/about_6102496_forensic-science_-hair-fiber-analysis.html

http://www.histology-world.com/photoalbum/albums/userpics/fig01.gif

http://www.ehow.com/about_5640929_forensic-science-hair-fiber-identification.html

http://videos.brokencurve.com/64f34f81fb6d47ddb2d6d076ab3ad1e0.jpg

http://www.swgmat.org/Forensic%20Fiber%20Examination%20Guidelines.pdf

http://www.gutenberg.org/files/17740/17740-h/images/fig10.jpg

http://paperproject.org/semgallery/images/silkATP2500x2.jpg

http://www.fbi.gov/about-us/history/famous-cases/the-lindbergh-kidnapping/lindberg_note.jpg