Microscopic characteristics include the pattern of the medulla, pigmentation of the cortex, and types of scales on the cuticle (Figure 3-12). Medullary index can be measured. Typical magnification for viewing hair is between 40 times and 400 times.
What is hair microscopic?
air microscopy, or microscopic hair analysis, is the practice of comparing hairs under a microscope to determine whether they came from the same person . 1 Examiners look at hair color, chemical treatment, pigment aggregation, shaft form, and other observable characteristics. Hair analysis is a form of pattern matching.
What are the characteristics of hair?
Hair tends to be very soft, thin, shiny, oily, poor at holding curls , difficult to damage. Hair characterized by volume and body. Hair tends to be bone-straight, coarse, difficult to curl. Hair has definite “S” pattern, can easily be straightened or curled, usually receptive to a variety of styles.
What is microscopic hair comparison?
Microscopic hair comparison is basically what it sounds like: a forensic analyst compares one or more hairs relevant to a crime . ... Thus, the analyst seeks to determine whether the suspect’s sample hairs are consistent in these characteristics with the unknown hairs.
What are the 3 microscopic layers of hair?
Each hair shaft is made up of two or three layers: the cuticle, the cortex, and sometimes the medulla . The cuticle is the outermost layer. Made of flattened cells that overlap like the tiles on a terra-cotta roof, the cuticle protects the inside of the hair shaft from damage.
What is the largest part of hair?
In humans, the cortex is the largest part of the hair shaft. The cortex is the part of the hair that contains most of the pigment granules (melanin) that give the hair its color (Figure 3-5).
How do you identify animal hair?
Human hair normally has fragmental medulla and never contains patterned medulla. Most animal hair contains continuous or patterned medullas. (See Figure 5.) Specific species of animals can be identified by comparing the medulla pattern with standard reference slides under the microscope .
What can hair samples detect?
- marijuana.
- amphetamines, including methamphetamine, MDMA (ecstasy), and MDEA (eve)
- cocaine.
- opiates, such as heroin, codeine, and morphine.
- phencyclidine (PCP)
What can a hair sample tell you?
You can’t wash them out. Because of that, your hair can reveal if you ‘ve been using drugs like opioids, cocaine, amphetamines, and cannabis . While a urine test will reveal if you’ve used drugs in the last several days, hair testing can show if you’ve done drugs over the past 3 months.
What are the four main characteristics of hair?
- texture. the size or diameter of the hair shaft. ...
- porosity. The ability of hair to absorb and hold moisture and liquid. ...
- tenacity. the degree of difficulty with which the cuticle can be penetrated. ...
- density. -the quality of number of hairs per square inch on the scalp. ...
- elasticity.
What are the four hair characteristics?
Each person has a unique texture. There are four main types of hair texture: Type 1 – straight, Type 2 – wavy, Type 3 – curly and Type 4 – tightly curled . The hair type and texture can be further broken down into a, b and c based on the hair’s curl pattern, density, porosity, width and length.
What are the two characteristics of hair?
The main physical proprieties of the hair depend mostly on its geometry; the physical and mechanical properties of hair involve characteristics to improve: elasticity, smoothness, volume, shine, and softness due to both the significant adherence of the cuticle scales and the movement control (malleability), as well as ...
Is microscopic hair analysis reliable?
Comparison microscopy resulted in 100 percent accuracy in associating the correct questioned hair with its known source, showing that they could reliably associate a questioned hair with a known sample.
Is microscopic hair analysis admissible in court?
The microscopic examination of hair using the comparison microscope has been the accepted standard technique for the examination and comparison of hairs for approximately the past 60 years, and, as such, this technique has been accepted by both State and Federal courts throughout the United States , in all U.S. ...
How many hair samples should be submitted for a comparison?
Further, in making comparisons, examiners use a “sample” (approximately 10) hairs from the known subject to compare with an unknown hair to see if characteristics from the unknown hair are present in the array of known hairs.
