Hair+Chapter+project+LD

__Describe & Introduce:__

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. Its purpose 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

The reason that hair is important in crime scene investigation is because in each person hair can have many different characteristics, that even without DNA can link or narrow down suspects. It can vary in color, texture, length, diameter and shape. The cross section can be different, it can be circular, irregular, triangular, or flattened, this determines the curl, wave or straightness of the hair. Hair can have many different textures younger people generally have softer more fine hair and older people have tough or coarse hair. Investigators can immediately tell if a hair has been dyed when they look at a strand under the microscope. One person may have many different hairs on their head, one strand may not categorize every strand on that persons head. An investigator will usually take at least 50 hairs from a suspects head due to the variation of colors and types. (25 are usually collected from the pubic region) Ex. someone who's hair is turning gray

__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 develops in 3 different stages:__
 * Anagen** stage (growing)- lasts the first 1,000 days, 80-90% of hair is in this stage
 * Catagen** stage(growing and developing)- is when the hair is changing and growing, it is responsible for 2% of the growth and development of hair
 * Telogen** stage(dormant) - hairs are easily lost during this stage because it is the final stage in which hairs are finished growing, 10-18% of hair on a humans head are in this stage

__Identify various parts of hair:__ There are two main parts of hair: The Follicle and the Shaft. The Follicle is the part that is located in the skin, it is attached to blood vessels that hold body nutrients and help the hair grow. The Shaft is made completely out of protein, this protein is called Keratin, this protein makes the hair strong and flexible. The Shaft has three layers: The Medulla is located inside of the hair. It is a tube that runs in the center, this tube is filled with cells or in some cases can be hollow. Scientists can use the medulla to make 5 different categories to classify a strand of hair under. This is because the medulla can change from person to person, the tube can once again be filled with cells or hollow, absent, fragmented, segmented, or it can be doubled or continuous, it can also have pigment or have no pigmented. The Cortex is in the center of the strand. It is the largest part of the shaft and it holds the majority of the melanin (pigment granules) and gives off the majority of the color. The amount of pigment in a hair differs from person to person and can be looked at under the compound microscope. The Cuticle is located on the outside of the hair, it is the thin outer layer. It protects the inner layer of the hair because it is made of scales that overlap each other. These scales can help in an investigation because a scientist can determine the age of a certain part of the hair by looking at which way the scales are pointing. When chemically testing for drugs, toxins or metals present in the hair, they can then specify the point in time in which the person was exposed to such things.

Different treatments one goes about putting on their hair tampers its original form 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. 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.

__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 Medullary index: The medulla in humans is smaller than in animals Cuticle type:

__Methods used to investigate hair found on a crime scene:__ 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.

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
 * 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:__
 * 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.
 * 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.
 * 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.
 * 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.

__Techniques For Investigating a Hair:__
 * 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.
 * Neutron Activation Analysis**:

Important words & Vocab:

__Definitions__:
 * Class Evidence**: Material that connects an individual or thing to a certian group.
 * Comparison Microscope**: A compound microscope that allows the side-by-side comparison of samples, such as hair or fibers
 * Cortex**: The region of a hair located outside of the medulla containing granules of pigment
 * Cuticle**: The tough outer covering of a hair composed of overlapping scales
 * Hair Follicle**: The actively growing root or base of a hair containing DNA and living cells
 * Individual Evidence**: A kind of evidence that identifies a particular person or thing
 * Keratin**: A type of fibrous protein that makes up the majority of the cortex of the hair
 * Medulla**: The central core of a hair fiber
 * Melanin Granules**: Bits of pigment found in the cortex of a hair
 * Neutron Activation Analysis**: A method of analysis that determines composition of elements in a sample
 * Trace Evidence**: Small but measurable amounts of physical or biological material found at a crime scene

NAA- Neutron Activation Analysis - Process that tests "for the presence and concentration of various elements in a sample" of hair

Examples of how topic is important in crime solving:

Gaetane Bouchard, 16 year old girl body found in 1958 had many strands in her hand, Using NAA thaey determined that the ratio of sulfer to phosphorus was closer to vollman, a suspect in the crime, than her own hair.This evidence was used to convict a Vollman, (first time in history NAA hair analysis was used to convict a criminal in a court case)

Determine if two examples of hair are likely to be from the same person:

Calculate medullary index for hair:

Distinguish hairs from individuals belonging to the broad racial categories: (Chapter 3: The study of hair)



comparison microscope