Hair and fibre are two of the most important resources in Forensic Science and are often responsible for providing valuable clues as to the identity of an assailant or attacker. The discovery of hair on the body of a victim or on the clothes of someone who has been the victim of an assault can often be used to determine race and sex.
What is the importance of hair in forensic science?
In any struggle between victim and attacker hairs and fibres from one are inevitably transferred to the other. The importance of hair in criminal investigation was realised at an early stage in the development of forensic science, and one of the first scientific papers on the subject was published in France in 1857.
How are hairloss and fibre collected for forensic science?
Hair and fibre are collected at varying points throughout the forensic science process but most notably at the scene of the crime and at the autopsy stage.
What information can be obtained from hair and fibres from crime scenes?
Examination of hair and fibres from a crime scene or suspect can yield a wealth of information. Hair and fibres can be used in helping to reconstruct events. Collection of hair and fibres can indicating contact with surfaces or individuals and so where individuals have been.
How do forensic scientists determine if hairs are real or fake?
If the hairs came from a human, forensic scientists compare the hairs found at a crime scene to the hairs taken from a suspect. This examination will determine if the suspect was indeed at the crime scene.
Why are hair and Fibres useful in forensics?
Hair and fibres can provide valuable clues about the identity of an assailant or attacker. The discovery of hair on the body of a victim or on the clothes of a victim of an assault can often be used to determine the assailant or attackers' race and sex.
What is the importance of hair in criminal investigation?
Hair evidence can be an important element in solving crimes because it can put a victim and suspect together at a crime scene. Hairs can be transferred directly or from one person to another, or through indirect means.
What is the importance of fibers in criminal cases?
By matching fibers at the scene of a crime to items belonging to a suspect, investigators are able to place individuals at a crime scene. The problem with fiber evidence (particularly when discussing clothing) is that cloth items are generally mass produced.
Why are hair and fibers useful evidence?
The transfer of hairs and fibers and their discovery as trace evidence can be critical in linking a suspect to a victim or to a crime scene.
How do hair and fibers solve crime problems?
Hairs found on a victim routinely point to a suspect and because DNA analysis can often be done, this provides a definitive identification of the perpetrator. Likewise, fibers obtained from victims clothes or in the area of the crime scene can guide investigators in the direction of a particular suspect.
Why do fibers have such importance in the examination of materials evidence?
Like hair, fibers are considered class evidence. Fibers have probative value because they can create connections, or associations. For example, a suspect may deny he was ever in a particular place or ever in contact with a particular person.
Why might fibers be important to forensics quizlet?
Fibers are an important item of trace evidence because their individuality can show the way they was made, the type of fabric they were in, and whether they are natural or manufactured. Forensic scientists can also match fibers at torn edges to identify a fabric or an item of clothing.
What is hair and fiber analysis?
Hair - Analysts can tell investigators if individual hairs are human or animal, and in the case of human hair, where on the body the sample originated. Samples can be tested to determine the color, shape and chemical composition of the hair, and often the race of the source individual.
Why is hair considered Class evidence?
Hair is considered class evidence because people of certain ethnic groups have unique characteristics for their hair. These unique characteristics are generally found for that group (although there may be variations). An example would be individuals of Asian heritage having straight hair with a thick cuticle.
Has hair helped solve a crime?
And because humans shed about 100 hairs a day from their heads, hair sometimes ends up at crime scenes and, as such, is known as “trace evidence.” When an investigator finds hair at a crime scene or on a crime victim, they can send the hair to a forensic scientist, who can analyze it.
What can hair found at the crime scene tell investigators?
Evidence That May be Collected. Hair - Analysts can tell investigators if individual hairs are human or animal, and in the case of human hair, where on the body the sample originated. Samples can be tested to determine the color, shape and chemical composition of the hair, and often the race of the source individual.
What is the purpose of hair?
The most important function of hair in mammals is that of insulating against cold by conserving body heat. The differing colours and colour patterns in hair coats can also serve purposes of camouflage and of sexual recognition and attraction among the members of a species.
What is the basic unit of raw material in textile production?
Fibres are the basic unit of raw material in textile production having suitable length, pliability, and strength for conversion into yarns and fabrics. A fibre of extreme length is a filament. Fibres can occur naturally or can be produced artificially.
What is cloth made of?
Most cloth is made of fibres woven or intertwined in some way. The kind of fibre and the way in which it is intertwined determine the character of the resulting cloth. More often, the police have only tiny fibres with which to work. It is surprising how often such fibres are left behind, or picked up, by the criminal.
What is the purpose of hair and fibres?
Examination of hair and fibres from a crime scene or suspect can yield a wealth of information. Hair and fibres can be used in helping to reconstruct events. Collection of hair and fibres can indicating contact with surfaces or individuals and so where individuals have been.
How to identify a fibre?
The first step in identifying a fibre is to determine its type. Not long ago, most fabrics were made of wool, cotton, linen or silk. It was easy to identify them just be feeling and looking. Today a wide variety of synthetic fibres has appeared on the market, and manufacturers have learn how to combine many fibres in making a single fabric, making it difficult to analyse completely or identify all fabrics.
Why is hair important?
Hair picks up the poisons from the bloodstream, and it is possible to work out the approximate strength and frequency of the dosage by analysis. Hair can be used in helping to reconstruct events.
How old was Leonard Mills when he was arrested?
Minute inspection of her clothing revealed some hairs which were immediately sent to the forensic laboratory, where microscope examination showed them to be identical with the head hair of Leonard Mills, an 18 year old clerk and the chief suspect.
What is the cuticle?
cuticle;#N#The outermost layer or sheath of the hair of mammals.#N#The strip of hardened skin at the base and sides of a fingernail or toenail. 1 The outermost layer or sheath of the hair of mammals. 2 The strip of hardened skin at the base and sides of a fingernail or toenail.
What happens to the hair in the telogen phase?
During the telogen phase, the hair is anchored in the follicle only by the root, which is club-shaped. The germ cells below the club-shaped root will give rise to the next generation of an anagen hair.
What is the transition period between the anagen and telogen phases?
In the telogen phase, the follicle is dormant or resting. The transition period between the anagen and telogen phases is referred to as the catagen phase. Hairs are routinely lost during the telogen phase and often become a primary source of evidentiary material.
What is the phase of hair growth?
As hairs undergo a cyclical growth (anagen) and resting phase (telogen), the visible microscopic characteristics are sufficient to determine the phase of growth of the hair. During the anagen phase, the hair is actively growing, and materials are deposited in the hair shaft by cells found in the follicle.
Why is it important to get head hair samples?
Environmental alterations can result from exposure to excessive sunlight, wind, dryness, and other conditions. Because these hairs can be affected by a number of environmental and chemical conditions, it is recommended that head hair samples be obtained as soon as possible from suspects and victims of crime.
Where are hairs found in the human body?
Considerable variability also exists in the types of hairs that are found on the body of an animal. In humans, hairs found on the head, pubic region, arms, legs, and other body areas have characteristics that can determine their origin.
What is hair evidence?
Hair Evidence. Hairs, which are composed primarily of the protein keratin, can be defined as slender outgrowths of the skin of mammals. Each species of animal possesses hair with characteristic length, color, shape, root appearance, and internal microscopic features that distinguish one animal from another.
What are the components of the hair?
Metabolically active and dividing cells above and around the dermal papilla of the follicle grow upward during this phase, to form the major components of the hair—the medulla, cortex, cuticle, and accompanying root sheath. In the telogen phase, the follicle is dormant or resting.
How can fiber be transferred?
A practice of Locard’s Principe is Fiber Analysis. Transfer of fiber can happen during close contact with the victim or suspect. Textile fibers can also be transmitted from rugs or blankets by contact between two individuals, between an individual and an object, or between two objects. Analysis of fibers that are found on a victim will involve determining the types of fibers present at the scene. Fibers found throughout the crime scene will not be as significant as a fiber found on a victim (that is not present anywhere else at the scene). This is because if a similar fiber is found on a suspect, it can be a powerful piece of evidence linking the suspect to the crime.
When was hair first used in forensics?
One of the first forensic science reports involving the scientific study of hair was published in France, in 1857 . This introduced the idea of hair and fiber analysis and the field expanded fast in the early 20th century after microscopic hair examination became known. In 1883 a historical text on forensic science was published “The Principles and Practice of Medical Jurisprudence” by Alfred Swaine Taylor and Thomas Stevenson, where a chapter on using hair in forensic investigations was written and it included drawings of human hairs under magnification.
What does it mean when forensic scientists compare the hairs found at a crime scene to the hairs taken from
If the hairs came from a human, forensic scientists compare the hairs found at a crime scene to the hairs taken from a suspect. This examination will determine if the suspect was indeed at the crime scene.
How can forensic scientists determine what part of the body the hairs came from?
Forensic scientists can determine a number of things from analyzing hairs found at crime scenes. The clues that hairs reveal include what part of the body the hairs came from, the race of the person they came from, if the hairs shed naturally or were pulled from someone's head, and whether the hairs were color treated.
Why is hair evidence important?
Hair evidence can be an important element in solving crimes because it can put a victim and suspect together at a crime scene. Hairs can be transferred directly or from one person to another, or through indirect means. An example of indirect transfer would be when people shed hairs onto their clothes and then transfer them to another person.
What is the purpose of forensic hair analysis?
Examination of Hairs. When forensic scientists analyze hairs, they first determine if the hairs came from a human or an animal. If the hairs came from an animal, they then work to identify the species of the animal.
Where are hairs taken from?
Likewise, when pubic hairs are collected from a suspect's body, they are taken from several areas of the pubic region.
Can animal hairs be linked to an animal?
Although animal hairs found at a crime scene cannot be linked to an individual animal, knowing the species can go a long way toward putting a suspect at the scene of a crime. For example, dog hairs may be found at a crime scene but it is discovered that the victim does not own a dog. If the suspect owns the breed of dog that the hairs came from, this evidence strongly suggests that the suspect and victim had contact.
Which area of the body gives the most evidence?
Hairs from the head and genital area yield the most evidence because of their unique nature. Although hairs from the face, chest and underarm can put someone at a crime scene, they are usually not tested by forensic scientists.
Why is hair important for DNA analysis?
Hair samples are one of the most important resources in the forensic analysis of crime scenes, often providing valuable information that can help to lead to the identification of a suspect or victim. Hairs are slender fibrous outgrowths projecting from the skin that possess different microscopic ...
What microscope do forensic scientists use to see hair samples?
Forensic analysts use an instrument called a comparison microscope to view a known hair sample and an unknown sample alongside one another to see if they share similar characteristics and could have come from the same source.
Why is hair used in forensics?
Hair can also be used to extract DNA for analyses that can help to narrow down who may have been involved in a crime.
How many hairs do humans shed?
Humans shed an average of approximately 100 head hairs per day, and because hair can be easily transferred during physical contact it is commonly submitted as forensic evidence to help establish associations between people (e.g. a victim and suspect) and/or people and a crime scene.
What is animal hair?
Animal hairs found on items of evidence can link a suspect to a crime scene or a vehicle or location where a victim was held . Hairs from a pet the suspect owns, for example, may also be transferred to the victim when a suspect makes physical contact. If the hair is human in origin, analysis can help to distinguish between individuals based on ...
What is the test for DNA in hair?
If so, the sample can be tested using a nuclear DNA testing procedure called Short Tandem Repeat (STR) analysis .
What factors affect the robustness of hair association analyses?
Many factors affect the robustness of hair association analyses, including variations in the adequacy of equipment and staff experience and training. Although hair microscopy is a valuable tool to use for identification purposes, accurately determining a statistical probability of a given association is challenging, ...
What are the natural fibers used in fabric?
Many different natural fibers originating from plants and animals are used in the production of fabric. Cotton fibers are the plant fibers most commonly used in textile materials, with the type of cotton, fiber length, and degree of twist contributing to the diversity of these fibers.
What is the difference between immobile and suspect clothing?
If the victim is immobile, very little fiber loss will take place, whereas the suspect’s clothing will lose transferred fibers quickly.
What is the difference between primary and secondary transfer?
A primary transfer occurs when a fiber is transferred from a fabric directly onto a victim’s clothing, whereas a secondary transfer occurs when already transferred fibers on the clothing of a suspect transfer to the clothing of a victim.
Why are fiber associations important?
The wide variety of fiber types, fiber colors, and fabric types can make fiber associations very significant because the value of a fiber association depends on the type of fiber, the color of the fiber, the number of fibers transferred, the location of the recovered fibers, and other factors.
Why do newer fabrics shed more?
Some newer fabrics may shed more readily because of an abundance of loosely adhering fibers on the surface of the fabric. Some worn fabrics may have damaged areas that easily shed fibers. Damage to a fabric caused during physical contact greatly increases the likelihood of fiber transfer. Fabric Source Determination.
Why do victims of homicide tend to retain transferred fibers for a longer period of time?
For example, the clothing of a homicide victim would tend to retain transferred fibers for a longer period of time because the victim is not moving. Emergency personnel, medical examiners, and investigators must handle the victim’s clothing carefully to minimize fiber loss.
How does color affect fiber?
Color influences the value given to a particular fiber identification. Often several dyes are used to give a fiber a desired color. Individual fibers can be colored prior to being spun into yarns. Yarns can be dyed, and fabrics made from them can be dyed.
