History of Hair and fiber analysis
Hair and fibers are easily transportable; this makes hair and fibers
great pieces of evidence left behind by the criminal. The study of hair linked to crimes first began with French scientist Edmond Locard. Locard realized that many fibers and pieces of hair were transported easily and exchanged, by using that theory he created the "Locard Exchange Principle" which stated that if there is any contact between two items, there will be an exchange. Hair usually pertains to one person only, but according to German pathologist Rudolf Virchow, hair does not match positively enough to link a suspect to the crime. Paul L. Kirk wrote a textbook called “Crime Investigation” which sets the fundamentals for microscopic hair analysis for scientists today.
Hair and fibers are easily transportable; this makes hair and fibers
great pieces of evidence left behind by the criminal. The study of hair linked to crimes first began with French scientist Edmond Locard. Locard realized that many fibers and pieces of hair were transported easily and exchanged, by using that theory he created the "Locard Exchange Principle" which stated that if there is any contact between two items, there will be an exchange. Hair usually pertains to one person only, but according to German pathologist Rudolf Virchow, hair does not match positively enough to link a suspect to the crime. Paul L. Kirk wrote a textbook called “Crime Investigation” which sets the fundamentals for microscopic hair analysis for scientists today.
labeled parts of a complete human hair
Major types of fibers
There are many fibers that are used for thousands of things around the world. The five most common fibers are wool, polyester, cotton, nylon and silk. Each fiber contains a different weave pattern making it unique. Therefore, the fiber identified on a victim’s body could be traced back to the clothing that the criminal wore at the time of the crime.
Hair and Fiber collection techniques
Hair samples could be obtained at the crime scene or during the autopsy stage. These hair or fiber samples are collected in varying vials, tubes and grip seal bags so that cross contamination may not occur between the time of collection and the time of proper analysis. During the autopsy stage, the pathologists will scrape the underside of the victim’s nails to find any trace of hair, skin, or fibers that might have been picked up during a struggle with the attacker. Comparison of the fibers takes place in a later stage.
Hair samples could be obtained at the crime scene or during the autopsy stage. These hair or fiber samples are collected in varying vials, tubes and grip seal bags so that cross contamination may not occur between the time of collection and the time of proper analysis. During the autopsy stage, the pathologists will scrape the underside of the victim’s nails to find any trace of hair, skin, or fibers that might have been picked up during a struggle with the attacker. Comparison of the fibers takes place in a later stage.
Typical Hair and fiber analysis.
Scientists analyze hair and fibers by taking traces of the substances going through the bloodstream of the individual. As the hair grows, the substances harden, leaving a long trace of what is in the blood of the person. Scientists use a variety of techniques to analyze the hair. For example, A physical examination of the hair found in the crime scene usually is examined under a microscope. This can show details like the race a person belongs to by the unique pattern of the hair. Evidence cannot be used to identify a single person, but this can be done if the hair has root or root sheath material attached, which can be used for DNA analysis of the hair
Reliability of Hair and fiber crime scene data
The reliability of hair and fibers in a crime scene has certain limitations, since the hair itself does not aid in identifying the “owner” if the hair sample. Yet, it can narrow the choices of the suspect based on the color of the hair sample, it could help to identify race. Yet, the same hair sample could also match with many other individuals. The same situation is encountered with fibers; the sample could belong to any kind of clothing, but if there is more information that can aid in the case, the fiber found can be the final word in determining guilt. Despite the limitations, hair and fiber evidence is greatly appreciated by the police.
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Unusual carpet fiber case
In 1982, Kristen Lea Harrison was abducted from a ball field in Ohio and her body was found six days thirty miles away from where she was last seen. She had been raped and strangled. As she was being examined, the detectives noticed orange fibers in her hair that looked suspiciously like those that had been found on a twelve-year-old female murder victim from eight months earlier in the same county. Since they were made of polyester and were oddly shaped (trilobal), forensic scientists surmised that it was carpet fiber. In addition, a box found near Kristin's body and plastic wrap around her feet indicated that the killer had once ordered a special kind of van seat, but then leads dried up. Afterwards, a 28- year old woman was abducted and kept in man’s home, yet she managed to escape and report him to the police. The man was then searched along with his belongings. The carpeting in his van turned out to have the same fiber that had been discovered on the woman that had been previously murdered. The unique connection of the fibers allowed for the capture of the murderer, although simple evidence, the unique fiber aided in the salvage of many lives.
In 1982, Kristen Lea Harrison was abducted from a ball field in Ohio and her body was found six days thirty miles away from where she was last seen. She had been raped and strangled. As she was being examined, the detectives noticed orange fibers in her hair that looked suspiciously like those that had been found on a twelve-year-old female murder victim from eight months earlier in the same county. Since they were made of polyester and were oddly shaped (trilobal), forensic scientists surmised that it was carpet fiber. In addition, a box found near Kristin's body and plastic wrap around her feet indicated that the killer had once ordered a special kind of van seat, but then leads dried up. Afterwards, a 28- year old woman was abducted and kept in man’s home, yet she managed to escape and report him to the police. The man was then searched along with his belongings. The carpeting in his van turned out to have the same fiber that had been discovered on the woman that had been previously murdered. The unique connection of the fibers allowed for the capture of the murderer, although simple evidence, the unique fiber aided in the salvage of many lives.
Enjoyed the detailed picture of the hair sample! There seems to be a grammatical error near the beginning of the second sentence at the top, should it be "linked" instead of "liked"?
ReplyDeleteVery good information and pictures. There isn't too much text or too many pictures. The organization is perfect, I think the best I've seen. Very easy to follow.
ReplyDeleteI felt that the research was well done and organized. It showed comprehension of the material and overall good job.
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