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Lucy, Rebecca, Adelaid, Liz

Hair Chapter

- A forensic examine can tell scale patterns, roots, color, length, and shaft characteristics just by looking at a hair (under a microscope) - They can tell if hair was "forceably removed, damaged by burning, dyed or bleached,or cut by glass" - They can determine if a person was ill or poisoned - However a microscopic look cannot tell the owner
 *  Trichology ** is the study of hair

Hair does not decompose easily because of a tough outer coating. Human hair grows approximately 1.3 cm per month Hair is found on all animals, it is often called fur. The purpose of hair is to insulate the body, protect the body, and regulate the temperature of the body.

When a hair is found on a crime scene it can provide information concerning the race and the background of a suspect. A single hair can hold many different variations of a persons background, drug use, nutritional facts, and hold other chemicals an individual has been exposed to By chemically testing a hair an investigator can look for any of these clues to help determine a suspect

Hair found on a crime scene can be considered
 * Class Evidence** or **Individual Evidence**

If it is Class Evidence it cannot be used to specify an individual because the follicle is not attached. By identifying the type or color of the hair you can use that information to eliminate people belonging to a race or group that does not share the characteristics of the hair found. You can also use it to compare or link a suspect having similar characteristics belonging to the hair. It cannot directly link a suspect to the hair even if they appear similar.

If it is Individual Evidence the follicle is still in tact on the hair. DNA of the suspect can be determined and can link the hair to the individual.

In the late 1800's scientists began to recognize the significance of hair as trace evidence

**Trace Evidence**: Small but measurable amounts of physical or biological material found at a crime scene

Hair consist of two parts: The Follicle and the Shaft. __The follicle__ is a club shaped structure in the skin. At the end of the end of the follicle is a network of blood vessels that supply nutrients to feed the hair and to help it grow. - this is called the PAPILLA - surrounding the papilla is a bulb. A sebaceous gland, which secretes oil that helps keep the hair conditioned, is associated with the bulb. The erector muscle that causes the hair to stand upright attaches to the bulb. - Nerve cells wind around the follicle and stimulate the erector muscle in response to changing environment conditions. __The Shaft__ is composed of the protein KERATIN which is produced in the skin. Keratin is made up of a chain of amino acids that forms a helical, or spiral shape. These helices are connected by strong bonds between amino acids. these bonds make hair strong. the hair shaft is made up of three layers: an inner medulla, a cortex, and an outer cuticle. A good analogy for the structure of a hair shaft is the structure of a pencil: the painted yellow exterior of the pencil is similar to the cuticle. The graphite in the middle of the pencil is similar to the medulla. The wood of the pencil is analogous to the cortex of a hair. Human hair has cuticle scales that are flattened and narrow also called IMBRICATE. Animal hair had different types of cuticles.
 * The structure of hair:**

http://www.hoyu-usa.com/images/allabouthair_img_structure.jpg

The cuticle is a transparent outer layer of the hair shaft. - it is made out of scales that over lap one another and protect the inner layers of the hair - when examining a section of hair under a microscope, noticing the direction of scales point shows the younger and older ends of the hair. - cuticles can determine the presence of different drugs toxins or metals at a specifies point in time. - human hair has cuticle scales that are flattened and narrow, also called IMBRICATE
 * Cuticle:**

- the cortex is the largest part of the hair shaft. - it contains the most of the pigment granules (melanin) that give the hair color - the pigment distribution varies from person to person - if your pigment is large, your cortex will have uneven color distribution when viewed under a compound microscope.
 * Types of Cortex:**

- the center of the hair is called the medulla. - it can be a hollow tube, or filled with cells. -some people do not have a medulla, and some people have a fragmented one or segmented one, or some even have a double medulla - medulla contains pigment granules or lacks pigments. -forensic investigators classify hair into 5 different groups depending on the appearance of the medulla.
 * Types of Medulla**

 Continuous: One unbroken line of color Interrupted (intermittent) Pigmented line broken at regular intervals  fragmented or segmented : Pigmented line unevenly spaced  solid : Pigment area filling both the medulla and the cortex none No separate pigmentation in the medulla
 * Medulla Pattern: Description:**

- hair can vary in shape, length, diameter, texture, and color - the cross section of the hair may be circular, triangular, irregular or flattened, influencing the curl of the hair. - hair can be coarse(whiskers) or fine(children) - some furs are a mixture as in dogs coats, which often have 2 layers: one fine and one coarse - hair color varies depending of the pigment granules distribution and on hair dyes that may have been used. - hair varies from person to person - not all hairs on someone's head are exactly the same -suspects have have grey hairs along with brown hair - therefore 50 hairs are collected from the suspects head. Typically 25 hairs are collected from the pubic region.
 * Types of Hair:**



__Different parts of the body:__ One person has six types of hair on their body, each type can be distinguished by the shape of their cross section: Head hair- circular or elliptical cross section Eyebrow and Eyelash hair- circular cross section, generally have tapering ends Beard and Mustache hair- Triangular cross section, usually thick or even have a double medulla Underarm hair- Oval or triangular cross section Body hair- Oval or triangular cross section, arm and leg hair have blunt tips and are often frayed at the ends Pubic hair- Oval or triangular cross section

Hair proceeds though three stages as it developes: 1. stage one is called ANAGEN STAGE and last approximately 1,000 days. 80- 90 percent of all human hair is in the anagen stage. This is when the hair is in active growth when the follicle are rapidly dividing and depositing materials within the hair. 2. The CATAGEN STAGE: the hair grows and changes color: to gray. contains about 2 percent of all hair growth and development. 3. TELOGEN STAGE: hair is dormant or resting and hairs are easily lost. about 10- 18 percent of all hairs are in the telogen stage.
 * The Life Cycle of Hair:**

__Dying or chemically treating hair:__ Different treatments one goes about putting on their hair tampers its original form A scientist can take a color treated hair and determine the last time it has been dyed. They take the length of hair that is naturally colored and divide it by 1.3 (cm hair grows per month), and they can estimate or determine how many months the hair has gone un dyed. This can help to identify a suspect or victim in a crime.
 * Bleaching hair** makes it brittle and can change the aligning of the scales on the cuticle. It makes the hair turn yellow and removes pigment. '
 * Dying hair** will change the color of the hair shaft, cuticle and cortex. A scientist can usually distinguish a naturally colored hair and a dyed hair.

__Destingish between human and non human hair:__ Investigators can determine weather a hair is human or animal using a low power compound microscope by looking for some major differences:  Human and animal hair have many differences Pattern of pigmentation: Pigmentation in human hair is denser at the cuticle, and animal hair pigmentation is denser toward the medulla  Human hair generally maintains one solid color while animal hair are found in solid masses (ovoid bodies), and have banded patterns that often change abruptly The medulla in humans is smaller than in animals

Distinguish hairs from individuals belonging to the broad racial categories:
 * [[image:racial_ethnic_differences.jpg caption="racial_ethnic_differences.jpg"]] ||
 * racial_ethnic_differences.jpg ||

- Locards exchange principle: Whenever two objects are in contact, some transfer of material will occur. If a person is at a crime scene there is a very likely chance that they will leave trace evidence, a very common example of trace evidence is hair. - if someone is at a crime scene, he or she will leave some trace of his or her presence behind, or pick up some trace evidence from the crime scene - investigators collect trace evidence at a crime scene
 * Using hair in an investigation:**

Hair is collected from a crime scene by: Plucking surfaces or fabrics Shaking items Scraping surfaces Using tape to extract Large surfaces can sometimes use a small vacuum They carefully try and collect hairs directly from the place which they are found to avoid cross contamination.

When there are many hairs found on a crime scene or victim Investigators will take samples of hair from the 6 sources of hair on the body of the victim These hairs will be investigated, determined if human, and then compared.

When a hair is found, investigators will look at it macroscopically and microscopically. **Macroscopically** : They can see the length, color and curliness <span style="color: rgb(164, 10, 100)">**Microscopically** : They look at the types of scales found on the cuticle, the cortex pigmentation, and the medulla pattern and length

Magnification in a microscope for viewing hair is between 40 and 400 times

__Techniques Using Microscopes:__ <span style="color: rgb(211, 3, 86)">**Phase contrast microscopy**: This technique is useful for viewing small details in a hair, especially in translucent hairs. This is possible by using a compound microscope with special parts and lenses allows light to pass through the hair and allow for certian details and information to be seen that couldnt be seen using the comparison microscope. <span style="color: rgb(204, 0, 116)">**Fluorescence microscope** : This is useful when a hair that has been treated or dyed is found. When a fluoresced light is shined on a dye or chemical found on a hair it will change or appear a particular color that is different, this can let them determine what was used on the hair. <span style="color: rgb(158, 0, 77)">**Electron Microscope**: Electron microscopes can magnify the hair over 50,000 times. This is very useful in looking at fine and tiny details on the surface or on the interior of the hair. This is possible by applying a beam of direct electrons at the hair.
 * <span style="color: rgb(215, 4, 93)">Comparison microscope :** Very useful and common for hair analysis, it allows the scientist to view two different hair samples at the same time, it has two separate parts for each, this is important and useful when trying to compare a hair found on a scene to a hair of a victim or suspect.
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__Techniques For Investigating a Hair:__ <span style="color: rgb(168, 0, 78)">**Chemical Analysis:** Investigators use this method to determine the history of drug use, see toxins they have recently been exposed to or ingested. Scientists can also determine if a victim was poisoned. When a hair grows, it collects chemicals that the skin has absorbed. This process is done by releasing substances that the hair has been exposed to by dissolving the hair in an organic solvent that breaks down the keratin. They can then use the length of the hair and the rate of growth to determine a time line for the hair in order to see when it was exposed to the substance found on it. The hair is injected with high energy neutrons in a nuclear reactor. Different signals can be recorded that are found on the hairs, different gamma signals can be detected from different concentrations of elements on hairs. the probability of the hairs of two individuals having the same concentration of nine different elements is about one in a million.
 * <span style="color: rgb(255, 0, 131)"> NEUTRON ACTIVATION ANALYSIS (NAA) **:- can identify up to 14 different elements in a single two- centimeter- long strand of human hair.

- follicular tag: blood and tissue attached to the follicle may be analyzed - the blood proteins can be isolated to identify the blood type of a suspect. - DNA analysis can also preformed on hair follicle cells. - DNA analysis of the hair follicle provides an identification with a high degree of confidence, whereas analysis of the hair shaft usually provides class evidence only. - if a microscopic match between a suspect and a sample is found, then the sample will be forwarded for blood and DNA testing
 * testing the hair follicle:**

Example of its use in an investigation: Gaetane Bouchard was a 16 year old girl who's body was found in 1958. Her body was found with many strands of hair in her hand, Using NAA investigators determined that the ratio of sulfur to phosphorus was closer to Vollman, a suspect in the crime, than her own hair.This evidence was used to convict a Vollman of the murder. (first time in history NAA hair analysis was used to convict a criminal in a court case)

__Definitions__: <span style="color: rgb(189, 10, 97)">**Class Evidence** : Material that connects an individual or thing to a certian group. <span style="color: rgb(163, 0, 78)">**Comparison Microscope** : A compound microscope that allows the side-by-side comparison of samples, such as hair or fibers <span style="color: rgb(35, 11, 11)"><span style="color: rgb(197, 2, 68)">**Cortex**: The region of a hair located outside of the medulla containing granules of pigment <span style="color: rgb(255, 0, 173)">**Cuticle** : The tough outer covering of a hair composed of overlapping scales <span style="color: rgb(214, 0, 142)">**Hair Follicle**: The actively growing root or base of a hair containing DNA and living cells <span style="color: rgb(248, 42, 137)">**Individual Evidence**: A kind of evidence that identifies a particular person or thing <span style="color: rgb(221, 8, 135)">**Keratin**: A type of fibrous protein that makes up the majority of the cortex of the hair <span style="color: rgb(251, 65, 163)">**Medulla**: The central core of a hair fiber <span style="color: rgb(248, 42, 176)">**Melanin Granules**: Bits of pigment found in the cortex of a hair <span style="color: rgb(244, 52, 204)">**Neutron Activation Analysis**: A method of analysis that determines composition of elements in a sample <span style="color: rgb(252, 3, 171)">**Trace Evidence**: Small but measurable amounts of physical or biological material found at a crime scene

Quiz- http://www.fbi.gov/page2/march05/hair031605.htm