Forensic ScienceHair and FibersPlease find the PowerPoints on our Google Classroom.Please continue to check your student email. I am working to host a Zoom meeting and will send you an invitation through email.Please turn in work using photos and email or the Google Doc on Google Classroom.Hope you all are well and you are missed.

Hair and Fiber

As members of the animal kingdom we share in many with our four and more legged companions.

One of the characteristics is the presence of body hair.

Originally the reason for body hair was warmth and protection.

From the viewpoint of criminal investigations, body hair is a useful tool.

Because of its value hair must be treated with care. Never use fingers, use tweezers(clean) Never scotch tape hair. Use druggist fold as container-placed inside an envelope.

Let’s look at the parts of the hair.

A. Is it hair?

Hair has two parts- the bulb, pulled or plucked hair roots including the cell of the root are the specimens necessary for submission for DNA profiling. A hair shaft which has fallen out naturally or has been cut will not contain a sufficient amount of DNA. The second part the shaft grows outward away from the root end. In this we look for the presence of a cuticle, cortex, medulla.

Cuticle-outside cover -the cuticle is a comprised of overlapping scales which always point toward the tip.

Cortex-walls- comprised of long, flat cells which give the hair its pliability.

Medulla- core- the coloring agent or pigment responsible for the coloring of the hair is found in the medulla.

B. Is it human?

We look for scale patterns. We are able to determine the difference between species.

C. If not human, which animal?

Again, which one can be determined by the scale patterns.

D. If human-what race?

Primarily look at 3 primary races

Caucasian, negroid, Mongolian. We look at the cortex to determine the differences.

C- cortex round and even distribution of color.

N- ribbon appearance to cortex and coloring in clumps.

M- hair straight -color distribution between two others

Mixed marriage - dominant characteristics found.

E. Can't determine age and sex.

F. Part of the body it came from?

We must take a cross section of the cuticle to determine what part of the body the hair was from. The three parts of the body include: face (triangle shape), head (round shape), pubic (a bean shape).

We can also look at the physical characteristics such as short mucus clinging - nasal hair and long kinky debris - pubic or underarm.

G. There is also miscellaneous information that can be obtained.

a. bleached, dyed, colored - look at cortex and cuticle to determine the difference in color.

b. environment/occupation/ hangouts - debris can get caught in the scales of our hair. Think of me always in from of a chalk board. The chalk dust gets caught in the scales of my hair.

c. certain illness - these illnesses will result in deviations in the scale patterns.

H. How was the hair separated from the body?

There are several indicators that help us to determine how the hair was removed. By looking at the shape under a microscope we can determine the method. Cut hair has a sharp edge to it. We can also determine how long ago the hair may have been cut. We do this by looking at the roundness off the cut edges. The hair grows approximately half-inch permanent. Natural instinct is to grow back to the original pointed shape. When hair is crushed, we observe a jagged edge. When hair is burned it is brittle curled and smells. When it is singed it smells and has a great color. When it is pulled there is no root and you can observe this stretching. When it is pulled and there is a root the shaft is curled, stretched, and pigmentation broken up by this stretching. If the hair fell out naturally the root is present, and nothing is abnormal in the appearance.

Fibers

Any discussion of hair evidence must also include some mention of its first cousin - fibers. These items of evidence include threads, cloth, twine, rope, and adhesive tapes.

Since fibers in hairs so similar in physical characteristics, the same precautions must be taken when handling such evidence. Collection techniques include tweezers, the druggist fold, no scotch tape, and care for air currents.

Types of fibers

There are basically for classes of fibers

Animal- which includes furs, wools, silks, horsehair, and animal hairbrushes.

Vegetable- which includes cotton, linens, jute, hemp, and sisal. Products such as ropes, clothes, paper, and packing materials may fall into this category.

Minerals- these include asbestos, glass wool, and fiberglass. Products such as insulation, body repairs, clothing, drapery, safe insulation, and fire proofing may fall into this category.

Synthetic- these include man-made fibers. Examples would be rayon, orlon, nylon, dacron. These fibers can be found in clothes, drapery, bindings, fishing lines, and hosiery.

Laboratory examination

In most cases, the laboratory conclusions are not positive evidence. Their findings may indicate the sample is "consistent with". How important this finding may be is directly related to how rare or how common the specimens may be in terms of availability.

Laboratory examination is can be divided into three types: physical, chemical, in discernible differences.

Physical examinations include determining colors, direction of twist of thread, diameter of the thread, number of fibers per ply, number of plies per strand and the number of strands.

Chemical examination includes type of fiber, and analysis for impurities.

Discernible differences of fibers-when we look for discernible differences, we look at medulla, cortex, and cuticle, the way in which the scale patterns are formed, any effect of fire on the fiber. Each fiber reacts differently.

Animal fibers: there is an identifiable medulla, cortex, and cuticle. When animal hair is subjected to fire it stops burning when removed from the flame and smells of proteins.

Vegetable fibers: there is no medulla or cortex but there is a definite cellular structure. With subjected to fire it continues to burn after the fire is removed and it will retain its shape after burning.

Mineral fibers: no visible medulla cortex or cellular structure with subjected to microscopic examination there's a crystalline structure. Mineral fibers do not burn.

Synthetic fibers: no medulla, cortex, cuticle or internal cellular structure. With subjected to fire usually melts before burning.

In addition to the examinations mentioned about, we can also do physical matches similar to that used in glass. We can also match cloths by identifying pattern and construction of thread dyes colors impurities.

MEDULLA The medulla is the core of a hair that is not always present. There are several types and patterns.

TYPES:

Continuous

Intermittent or interrupted--even

breaks in the medulla

Fragmented--breaks that are unevenly

spaced

Absent

PATTERNS: 

Uniserial--small blocks in a row

Multiserial--several rows of blocks across

Vacuolated--uneven pattern

Lattice--circular patterns

Amorphous--without a specific pattern

Can you determine source of the different animal medulla? What is the type and pattern of each of these medulla? ANSWERS

 

1.

Medulla Type: _____

Medulla Pattern: ____

2.

Medulla Type: _____

Medulla Pattern: ____

3.

Medulla Type: _____

Medulla Pattern: ____

4.

Medulla Type: _____

Medulla Pattern: ____

5.

Medulla Type: _____

Medulla Pattern: ____

6.

Medulla Type: _____

Medulla Pattern: ____

The hair shaft is comprised of 3 different cell layers:

1. Cuticle: •Translucent outer layer, which protects

the hair. •Flat cells layered in an overlapping formation that looks like shingles on a roof.

2. Cortex: •Middle layer made up of long thin cells firmly attached to each other and arranged lengthwise. •Location where nature creates natural hair coloring, a substance called melanin. •Provides hair with strength, elasticity and determines the texture and quality of hair.

3. Medulla: •Central core of the hair. •Composed of soft keratin.

Cross-Section of Human Skin Review:

A. Melanocyte B. Muscle  C. Sebaceous gland  D. Hair shaft  E. Epidermis  F. Dermis  G. Subcutaneous tissue  H. Fat  I. Arterial blood vessel  J. Sweat gland  K. hair follicle L. Pacinian corpuscle 

a. melanocyte: an epidermal cell that produces melaninB. muscle: a body tissue consisting of long cells that contract when stimulated and produce motion C. sebaceous gland: any of the small sacculated glands lodged in the substance of the derma, usu. opening into the hair follicles, and secreting an oily or greasy material composed in great part of fat which softens and lubricates the hair and skin D. hair shaft: the part of a hair projecting beyond the skin E. epidermis: the outer epithelial layer of the external integument of the animal body that is derived from the embryonic epiblast; specif : the outer nonsensitive and nonvascular layer of the skin that overlies the dermis F. dermis: the sensitive vascular inner mesodermic layer of the skin -- called also corium, cutis G. subcutaneous tissue: of or pertaining to tissue being, living, or made under the top layers of skin H. fat: animal tissue consisting chiefly of cells distended with greasy or oily matterI. arterial blood vessel: any of the vessels through which bright red, oxygenated blood coming back from the lungs circulates in the body .J. sweat gland: a simple tubular gland of the skin that secretes perspiration and in humans is widely distributed in nearly all parts of the skin -- called also sudoriferous glandK. hair follicle: the tubular epithelial sheath that surrounds the lower part of the hair shaft and encloses at the bottom a vascular papilla supplying the growing basal part of the hair with nourishment L. Pacinian corpuscle: an oval capsule that terminates some sensory nerve fibers esp. in the skin of the hands and feet 

CUTICLE SCALES--Can you name the pattern found in each animal hair below?

Mosaic Pectinate Imbricate Petal Diamond Petal Chevron

HUMAN CUTICLE SCALES DOG CUTICLE SCALE

HAIR MEDULLA

CAT COW HORSE

MUSKRAT RABBIT RABBIT

Trace Evidence I. Hair Analysis Questions

1. Describe what is meant by ‘associative evidence’.

2. Describe what a comparison microscope is and how it is used to analyze trace evidence.

3. What would be observed if a hair were forcibly removed?

4. Describe the growth cycle of a hair including the growth phases and how long each phase lasts.

5. Describe the difference between a ‘primary transfer’ and a ‘secondary transfer’.

6. If samples can’t be collected directly from a human or animal, where else could samples be collected?

7. Create a table to compare and contrast Caucasoid, Mongoloid, and Negroid hair.

8. How many and what type of hairs should be collected from a suspect for analysis?

9. Is it possible to use hair analysis to determine the age of an individual? Explain.

10. Is it possible to use hair analysis to determine the gender of an individual? Explain.

11. Define and describe the parts of the human hair on the diagram below.

12. Describe the differences in a human hair and that of an animal.

13.Explain the limitations of hair analysis as evidence.

14.Describe the terms anagen, telogen, and catagen stage.

15.What are the three classifications of racial origin for human hair?

16.List the body location(s) from which hair origination can be determined.

17. What other characteristics can be evaluated in the association of a recovered hair with a particular individual?

Name: ____________________________

A New Kind of Bad Hair Day

1. What are the two questions that remain regarding the validity of testing hair samples for the presence of drugs?

2. Define the following terms:

False Positive:

False Negative:

3. How long after use can cocaine and marijuana be detected in urine?

4. Explain the biology of how drugs get absorbed into hair.

5. From what part of the body is a hair sample normally taken? Why is it taken from there?

6. How is the hair sample prepared/processed for testing?

7. The test performed to measure the concentration of drug in the hair is called a(n) ____________________________________ test.

8. What point/issue regarding testing hair do toxicologists disagree on?

9. What is the cultural issue over hair testing?

10. Research: Search the internet/magazines for 3 articles published within the last 3 years

(2017-2020) that discuss the acceptance/validity of hair testing. Highlight the key points in the articles.

Trace Evidence Name ___________________________

Use the websites on the Forensic Science page of the Kid Zone at http://sciencespot.net/ to complete this worksheet.

1st Site: Wikipedia – Locard’s Principle

1. Edmund Locard was the director of the very first _____________ laboratory in existence, located in Lyon, ______________.2. His exchange principle states that "with _________________ between two items, there will be an_____________________."3. _____________ __________________ is any type of material left at—or taken from—a crime scene, or the result of ________________ between two surfaces.4. Why is evidence placed in a paper bag or envelope rather than a plastic one? _______________________________

2nd Site: AC Trace Evidence1. Hair is one of the most telling pieces of trace evidence that can be collected from a crime scene. Name two ways hairs may be used to help an investigation.1._________________________________________________________________________________________________________________________________________________________2._________________________________________________________________________________________________________________________________________________________2. Fibers from ____________, carpet, ____________ and other sources that are foreign to the crime scene may indicate that the initial attack happened somewhere else, or might point to where the suspect ____________ or ____________.3. Shattered ____________ might indicate where a victim has been held, such as in a hostage situation, and ____________ chips might tell the investigators what kind of ____________ the suspect drives.4. Dirt has different _________________ compositions in different areas of the same city and can tell investigators where a ____________ or ____________ has been. Similarly, certain kinds of dust – such as ____________ – can only be found in certain areas.5. Ballistics is the study of the marks and residue left by ____________ and ____________. A lot can be determined from the ____________ made by a bullet or by the gunshot ____________ on a victim’s skin.6. When a criminal uses a ____________ to break into a home, the type of tool used leaves tell-tale marks in ____________, metal, ____________ and other surfaces that can tell the investigators exactly what it was.3rd Site: Forensic Science Lab

1. One of the most important principles in a lab is that any item of _________________ that enters the lab must never come into contact with anything that could _________________ it.2. The ____________ Evidence Unit of a lab is an area where scientists look for clues in evidence such as hair, ____________, dust, fiber, and ____________ remains.3. A chemistry unit in a lab is used to test samples of ____________ and ____________ for alcohol, drugs and poisoning. Chemistry is also used in the analysis of synthetic materials such ____________, dyes and ____________.4. The serology unit specializes in the identification and analysis of _________________ and other bodily____________, as well as ________ sequencing.5. Material units are used to identify and analyze ____________, paints, ceramics, ____________ and wood in an attempt to trace a ____________ back to a possible ____________. The biology unit is in charge of analyzing all biological evidence such a ____________ and ____________.6. Firearms units test ____________ to see which weapon made the mark on an object or wounded or killed a person. To be able to carry out these tests, firearms specialists study the used bullet ____________ and use shooting ____________ to fire weapons, identify the bullet marks and establish the firing ____________.7. ____________________ is used to document crime scene evidence. Large labs also have ____________ and explosives experts as well as specialists in ____________, computer data, files, documents, audios and ____________ recordings.8. Click the link for “Interactive” in the menu at the left side of the page and then choose “Quizzes.” Try at least 3 of the quizzes. List the name of each of the quizzes you tried and your final score for each in the space below.

Quiz: __________________________________________ Score: _______________Quiz: __________________________________________ Score: _______________Quiz: __________________________________________ Score: _______________

You may visit any of the sites listed on the Forensic Science page!T. Trimpe 2006 http://sciencespot.net/