Topic 4 Flashcards
is one of the oldest forms of physical evidence. Its use is older than fingerprints. It is valuable because the hair of each kind of animal is different and distinct for all others.
Hair examination
– This refers to a specialized e epithelial outgrowth of the skin which occur everywhere on the human body except on the palm of the hands and the sole of the feet.
Hair
– This refers generally to long and stiff hair.
Real Hair
– This refers generally to short, fine at times curly and wooly hair.
Fuzz Hair
– This refers to portion of embedded in the skin.
Root
– This refers to portion above the surface of the skin. It is the most distinctive part of the hair.
Shaft
– This refers to distal end of an uncut hair shaft. It is refers sometimes to point.
Tip
– This refers to the outermost covering of the hair. It is consists of one layer of non – nucleated polygonal cells which overlaps like the scales on fish.
Cuticle
– This refers to the intermediate and the thickest layer of the shaft and is compose of elongated, spindle shaped fibrils which cohere. They contain pigment granules in varying proportion depending on the type of the hair.
Cortex
– This refers to the central canal of the hair that may be empty or may contain various sorts of cells more or less pigmented and begins more or less near the root
Medulla or Core
– This can be examine using the naked eye or under the microscope.
Color
– This refers to the brownish – black pigment in the hair, skin, etc. It is the chemical responsible for the color of the hair. Black and brown hair differs only on the amount of melanin. Red hair is thought to be due to iron.
Melanin
– Tip of the hair may show whether a hair has been cut. Tips of body hair become rounded from rubbing against the cloths. Hair of human usually shows a fine tip. Men’s hair tip is apt to be cutoff square.
Character of the Hair Tip if present
– The size, the general shape and the irregularity of the scales are observed.
Character of Cuticle
– Structural features is studied under the microscope. Cortex is embedded with the pigment granules that impart hair with color. It is the color, shape and distribution of these granules that provides the criminalist with important points of comparison between the hairs of the different individuals.
Character of Cortex
– Dyed hair can be distinguished from natural hair. Under the microscope dyed hair has a dull appearance and the color tone is constant, whereas natural is not and the individual pigment granules stand more shapely.
Presence of Dye in Hair
– This refers to the innermost layer of your hair. It consists of a soft, thin core of transparent cells and air spaces (Kingsley, 2016).
Medulla
– This refers to the relationship between the diameter of the medulla and the diameter of the whole hair usually expressed in fraction. Its determination is performed under a microscope provided with micrometer eyepiece.
Medullary Index (M.I.)
Contain heavy pigment distributed unevenly
A thin cross section
Hair is usually kinky with marked variation in the diameter along the shaft
Negroid Race Hair:
Hair contains dense pigment distributed more evenly than Negroid race hair.
Cross section of the hair will be round to oval in shape.
Hair is coarse and straight with very little variation in diameter along the shaft of the hair.
Usually contains a heavy black medulla or core.
Mongoloid Race Hair:
Hair contains very fine to coarse pigment and more evenly distributed than is found in Negro or Mongolian.
Cross section will be oval to round in shape
Usually straight or wavy and not kinky
Caucasian Race Hair:
cannot be definitely determined from a hair examination.
Sex
– They are more mature than any other kind of human hair.
Scalp Hair
– Coarse, curve, very stiff and often triangular in cross section.
Beard Hair
– Usually triangular in shape and very stiff.
Moustache
short stubby and have wide medulla. Eyebrow and eyelashes are usually very short and has a sharp tip.
Hairs from eyebrows, eyelid, nose and ear –
– Vary in thickness along the shaft and are immature but are somewhat similar to head hairs. They have fine, long tip ends.
Trunk hair
– Similar trunk hairs but usually are not so long or so coarse and usually contain less pigment.
Limb Hair
– Fairly long with unevenly distributed pigment. They vary considerably in diameter along the shaft and have frequently a bleached appearance. It has an irregular shape and structure. Looks like pubic hair but the ends are sharper and the hair is not so curly.
Axillary Hair
– Similar to axillary hairs but are coarser and do not appear bleached. Wirier, have more constriction and twists and usually have continuous broad medulla.
Pubic Hair
Identification of questioned hair
Comparison of questioned and known hair
Light Microscopy
Link the suspect to a crime scene. Control hairs match that of the suspect. Exclude the suspect from a crime scene, meaning that a control hair does not match the evidential hair.
Comparison Microscope
Determine the species, race, and somatic origin of a hair. In addition:
DNA on the follicular tag
Drug Test – to test and determine whether a drug was used.
Scanning Electron Microscope (SEM)
– it can be extracted from the root or follicular tag of on anagenic hair.
DNA Analysis
comes from both parents that lead to individualization.
Nuclear DNA (nDNA)
passed only from mother to offspring.
Mitochondrial DNA (mtDNA)
– Microscopic appearance is affected by natural biological fluctuations and environmental influences. Pubic hairs are less influenced. Several years may not severely impact on meaningful pubic hair comparisons.
Environmental toxins
yarn consists of fibers or filaments that have been twisted together.
Textile Fibers
In general and broad sense the word “textile” is derived from the Latin word “_____” and the French “_____”, to weave, hence fiber means that can be converted into yarn.
Latin textillis
French textere
– It is a preliminary macroscopic examination. A test that determines whether fiber is mineral, animal or vegatble fiber.
Burning or Ignition Test
– fibers smolders or burn slowly and give odor like that of burning feather
animal’s fibers
– odor strong, disagreeable; fumes turn lead acetate paper black or brown.
Wool
– odor not so pungent, fumes have no effect on lead acetate paper.
Silk
– fibers burn rapidly with a flame and give off but little smoke or fumes.
For vegetable fibers
– Frequently used to determine the general group to which a fiber belongs. It is not reliable for positive identification of fibers. In general, the vegetables fibers exhibit a yellow fluorescence in ultra – violet light, whereas the animal fibers show bluish fluorescence.
Fluorescent Test
– In general, it is the most reliable and best means identifying fiber. The fiber is placed on a glass slide, teased and covered.
Microscopic Examination
– Unicellular filament, flat, ribbon – like, twisted spirally to right or left on its axis, central canal or lumen broad uniform in diameter; cell wall thick, covered by a thin, structureless, waxy cuticle. Fiber tapers gradually to a blunt or rounded point at one end.
Cotton
– Straight, cylindrical, with occasional twists; evenly lustrous, smooth except for occasional transverse folds or wrinkles. Cuticle mostly lacking, lumen irregular in width.
Mercerized Cotton
– Multicellular filament, straight and cylindrical, not twisted and flattened, tapering to a sharp point. Cell wall thick, the lumen appearing as a narrow dark line in the center of the fiber. Filament marked by transverse lines at intervals causing fiber to appear jointed, resembling bamboo. Cross lines frequently interest appearing like the letter x.
Linen
– Smooth, cylindrical, lustrous threads, usually single but often double, the twin – filaments held together by an envelope of gum. More or less transparent, without definite structure.
Cultivated Silk
– Similar to cultivated silk but broader and less regular in outline. Marked by very fine longitudinal striations with infrequent diagonal cross – markings.
Wild Silk
– Cylindrical, lustrous, appearing like a glass rod. Microchemical reactions, dissolved rapidly by half saturated chromic acid; not colored by Millon’s reagent as in case of true silk.
Artificial Silk
– Easily distinguished by presence of flattened, over lapping epidermal scales not found on silk or any of the vegetable fibers
Wool
– If the sample submitted for analysis is fairly large, such as a piece of cloth or a number or large threads, it is suggested that a chemical analysis be made to supplement the microscopic examination and confirm the results obtained form that procedure.
Chemical Analysis of Fibers
– The fiber is stained with picric acid, Millon’s reagent, stannic chloride or iodine solution.
Staining Test
– If the fiber is white or light colored it is treated with the following chemicals. If dyed, the fiber is first decolorized by boiling in ether 1% hydrochloric acid, acetic acid or dilute potassium hydroxide.
Dissolution Test
