What aspect of the hair cortex is most important for the criminalist and why? The cortex derives its major forensic importance from the fact that it is embedded with the pigment granules that impart hair with color .
Why is the stage of hair growth important to forensic investigators?
Investigators often find hair at the crime scene (remember the Locard Exchange Principle, introduced in Chapter 1). Hair is considered class evidence and is useful in backing up other circumstantial evidence , such as by placing someone at the crime scene.
What is a follicular tag and why is it important to forensic scientists studying hair?
The follicular tag, a translucent piece of tissue surrounding the hair’s shaft near the root, is a rich source of DNA associated with hair . Mitochondrial DNA can also be extracted from the hair shaft. All positive microscopic hair comparisons must be confirmed by DNA analysis.
Why is hair important in forensic science?
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. ... Hair can also be used to extract DNA for analyses that can help to narrow down who may have been involved in a crime.
What is the single most important forensic feature of hair?
what remains the hair’s most characteristic forensic feature? a. Cuticle — outer covering of hair consisiting of scales that come in 3 shapes: imbricate, coronel, and spinous.
What is medulla in forensics?
Middle layer of the hair . Thickest layer containing most of the pigment giving hair its color and shape. Define medulla. Core of the hair which can be found in many patterns like hollow or filled, absent, fragmented, continuous, doubled, pigmented or unpigmented.
Why is it important to forensic investigators the stage of hair growth of fibers found at a crime scene?
Why is it important to forensic investigators to know the stage of hair growth of fibers found at a crime scene? It helps investigators if the hair is in the Anagen or Catagen stage because the tissue on the end of the hair can help the investigators run more accurate DNA analysis .
What aspects of the hair are useful in species identification?
The pattern of the cuticle scales, the type and the diameter of the medulla and/or the characteristics of pigmentation can be used for animal species identification as well as for differentiation between animal and human hair at crime scene (Brunner and Coman, 1974[3]).
What feature of hair is most important in making a species identification?
– The scale pattern is useful in species identification. The cortex is the main body of the hair shaft. it is embedded with the pigment granules that impart hair with color. granules provide the criminalist with important points of comparison among the hairs of different individuals.
What is a hair tag in forensics?
Follicular Tag. a translucent piece of tissue surrounding the hair’s shaft near the root that contains the richest source of NUCLEAR DNA associated with hair .
Why are hairs important to the analysis of drugs and poisons during an investigation?
Analysis of hair provides useful information regarding drug addiction history or drug toxicity . ... When compared with other biological samples, hair provides a larger window for drug detection. Drugs get deposited in hair through blood circulation by various mechanisms, after its administration.
Why is hair mostly considered Class evidence?
Hair is considered class evidence when the follicle is not attached because the follicle is the part that contains DNA . ... If no match is found, follicle can maybe show blood type through a blood test. If no match is found, follicle can be DNA analyzed to provide identification with high degree of confidence.
Why is the study of hair valuable in forensic chemistry?
Hair is a valuable tool for forensic scientists. It is more resistant to decay than most other body tissues and fluids , thus remaining intact far longer than other evidence. This durability makes hair one of the most frequently found pieces of evidence at crime scenes.
What does the cortex do in hair?
The cortex forms the main bulk and pigment (colour) of your hair . It consists of long keratin filaments, which are held together by disulphide and hydrogen bonds. The health of your cortex depends largely on the integrity of the cuticle protecting it.
What are the granules in the cortex and what do they determine?
The cortex contains granules. What are these granules and what do they determine? Spindle-shaped cortical cells aligned in a regular array, parallel to the length of the hair . The cortex is embedded with pigment granules that impart color to hair.
What are aspects of hair that one can detect when viewing hair under the compound microscope?
Hair viewed for forensic investigations is studied both macroscopically and microscopically . Length, color, and curliness are macroscopic characteristics. Microscopic characteristics include the pattern of the medulla, pigmentation of the cortex, and types of scales on the cuticle (Figure 3-12).
What is meant by the morphology of hair?
Morphology and Structure of Human Hair. – Hair consists of dead cells which are extruded from the base of the follicle . – Hair consist of two parts; the shaft, the root or follicle. The hair is formed by cells of the dermal papilla at the base of the follicle.
Are scales found on the cortex?
Scales are found on the cortex . Scales always point toward the tip of the hair. It is fairly easy to determine the body area from which a hair came. DNA may be found in the hair root and can be used to determine individual characteristics.
What material is found in the core cortex and cuticle of hair?
The main component of the cortex is a keratin coiled- coil protein phase. The proteins form intermediate filaments, which then organize into larger and larger fibres. The hair is surrounded by the cuticle, a dead cell layer.
What are irregularly shaped air spaces in the cortex?
| A B | cortical fusi Irregular shaped air spaces in the cortex of hair | interference patterns A phenomenon demonstrating the wave nature of light resulting from constructinve (additive) and destructive combinations of light waves |
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What characteristics features of hair do investigators look for when analyzing hair from a crime scene?
Their texture, size, damage, and shape are all useful characteristics in the comparison process. Another region of the hair is the innermost layer of cells called the medulla. This layer of cells may be continuous, discontinuous, fragmentary, or absent.
What is the part of the hair that is needed for hair analysis?
Why It Is Done
Hair analysis is used to provide DNA evidence for criminal and paternity cases. For DNA testing, the root of one hair is needed to analyze DNA and to establish a person’s genetic makeup. ... Hair samples that are taken close to the root can show what drugs were used up to 3 months before the test.
How do forensic scientists analyze hair?
The hair can be analyzed by determining the chemical makeup of the hair or extracting DNA from the hair follicle . Hair can also be analyzed through the use of a microscope or by simply comparing two or more hairs against one another.
What characteristic makes hair a useful forensic tool?
What characteristics make a hair a useful forensic tool? The color, the unique patterns, and textures and the opportunity to get DNA all help forensics analysis identify suspects.
What instrument is typically used to conduct forensic analysis on hairs found at a crime scene?
Microscopic hair analysis has traditionally been used in forensics as well. Analysts examine a number of different characteristics of hairs under a microscope , usually comparing hair taken from a crime scene and hair taken from a suspect.
Can the structure of a hair be used to identify racial origin?
Human hairs can generally be identified by racial origin , body area, and other comparison characteristics. Racial indicators apply primarily to head hairs.
Why is the medulla useful in species identification?
To identify different species of hair, it is necessary to look at the medulla pattern to determine the origin of the hair . The medulla pattern in human hair is fragmented or absent (except for the Mongoloid race), while in animals their medulla is continuous or interrupted (in a pattern).
Why are hair and fiber evidence considered Class 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.
What is one difference between the medulla in human hair and the medulla in animal hair?
difference between human and animal hair. – Medulla in a human is smaller (medullary index of less than one-third); and medulla in animals is very thick (medullary index of one-half or greater). – Cuticle in humans is imbricated; and the cuticle in animals is coronal or spinous.
What are the main structures of the hair?
The hair shaft is comprised of three layers: the cuticle, cortex, and medulla . The cuticle is the hair’s outer most layer which has shingle or scale like cells that overlap. These cells work defensively to prevent damage to the hair’s inner structure and to control water content of hair fiber.
What makes human hair different from an animal hair?
Pigment concentration: Human hair has even distribution of pigment throughout cortex, while animal hair is more concentrated toward the center/medulla area. ... Cuticle patterns: Human hair is imbricate pattern, while animals can have a range including coronal and spinous.
How does the structure of hair makes a difference in the world of forensic science or in determining paternity?
If the hairs came from an animal, they then work to identify the species of the animal. 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.
When was hair first used in the field of forensics?
The first use of forensic hair analysis occurred in 1855 during the murder trial of John Browning. Hairs on a rope found in the defendant’s home were visually compared to the victim’s hair and were judged to be identical in colour and length.
Why is hair microscopy used in forensic science?
Hair can provide crime investigators with important clues. ... The forensic scientist using a microscope can make even a single head hair yield information about the race, sex an age of its owner, and while hair does not have the same individual character as a fingerprint it can provide vital evidence.
Why are hair samples considered to be both useful and cumbersome trace evidence?
Why are hair samples considered to be both useful yet cumbersome pieces of trace evidence? no. it’s costly . ... A hair sample that measures 10.5 centimeters in length was found at a crime scene and assumed by investigators to have come from a female.
How does hair help forensics investigators establish a timeline?
– because of its tough outer coating, hair does not easily decompose. Hair found at crime scenes or secondary locations can be analyzed. ... – When the follicle or even a portion of the shaft of a hair is present , DNA evidence may be obtained from it, which may lead to individual identification.
What is the cortex?
The cerebral cortex is the thin layer of the brain that covers the outer portion (1.5mm to 5mm) of the cerebrum . ... The cortex also covers the cerebellum. The cortex makes up about two-thirds of the brain’s total mass and lies over and around most of the brain’s structures.
What are three hair properties for which the cortex is responsible?
- (Pigment or natural color.)
- (Elasticity.)
- (Weight.)
What is a cortex in anatomy?
In anatomy and zoology, the cortex (plural cortices) is the outermost (or superficial) layer of an organ . Organs with well-defined cortical layers include kidneys, adrenal glands, ovaries, the thymus, and portions of the brain, including the cerebral cortex, the best-known of all cortices.
