FORC_Midterms

• Semen


  A viscid whitish fluid of the male reproductive tract consisting of spermatozoa suspended in secretion of accessory glands
• Semen

  • Comes from 3 main structures in the male reproductive anatomy: Prostate, Seminal vesicles, Testicles
• Composition of Semen


  • Seminal Fluid/Plasma (90%)
  • Spermatozoa or sperm cells (10%)
  • Epithelial cells (<1%)
  • Crystals of choline and lecithin
• Normal sperm count

  • Concentration of spermatozoa should be at least 20 million per ml
  • Total volume of semen should be at least 2ml
  • At least 75% should be alive
• Hypospermia


  Less than 1.5ml
• Hyperspermia

  More than 5.5 ml
• Sperm cell

  • Head
  • Midpiece
  • Tail
• Where semen and seminal stains can be found

  • Vaginal contents of the victim
  • Rectal contents of the victim
  • Pubic hair
  • Skin around the genitals
  • Underclothing
  • Bed clothing
• Examination of Semen and Seminal stains

  1. Physical examination

  2. Microscopic examination

  3. Ultraviolet examination

  4. Chemical examination
• Florence test


  Preliminary test, presence of spermatozoa confirms the presence of seminal stains. Visible result: crystals of choline periodide
• Barberio's test


  Almost specific for human semen. Visible result: crystals which are slender yellow-tinted, rhombic needles with obtuse angle or appear as ovoid crystals
• Acid-phosphatase test


  Based on the high acid phosphatase content of human male ejaculation. Visible result: orange-red pigment
• Microscopic examination


  Purpose is to determine the presence of spermatozoa. Visible result: A small object with a pear-shaped head, behind which is a short neck and then a tail of about ten times as long as the head
• Hair


  A slender, thread-like outgrowth from a follicle in the skin of mammals
• Types of Hair


  • Real Hair
  • Fuzz Hair
• Parts of the Hair

  • Root portion embedded in the skin
  • Shaft portion above the surface of the skin
  • Tip - sometimes termed point
• Hair Root


  1. Anagen phase

  2. Catagen Phase

  3. Telogen Phase
• Hair Shaft


  • Cuticle
  • Cortex
  • Medulla
• Cuticle


  A protective coating made of overlapping scales that always point toward the hair tip
• Cuticle scale structures


  • Coronal (crown-like)
  • Spinous (petal-like)
  • Imbricate (flattened)
• Spinous or petal-like scales


  • Triangular in shape
  • Protrude from the hair shaft
  • Found at the proximal region of mink hairs and on the fur hairs of seals, cats, and some other animals
  • Never found in human hairs
• Imbricate or flattened scales


  • Overlapping scales with narrow margins
  • Commonly found in human hairs and many animal hairs
• Medulla


  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 shape


  • Most animals and humans: cylindrical
  • Cats: pearl shape
  • Deer: spherical occupying whole hair shaft
• Types of animal hair

  • Tactile hairs (whiskers) that are found on the head of animals and provide sensory functions
  • Guard hairs that form the outer coat of an animal and provide protection
  • Fur or wool hairs that form the inner coat of an animal and provide insulation
• Types of medulla

  • Continuous (Mongoloid head hair)
  • Interrupted (discontinuous)
  • Fragmented (trace)
  • Absent
• Medullary index


  Measures diameter of medulla relative to the diameter of the hair shaft expressed in fraction
• Cortex


  • Made of spindle-shaped cells aligned in a regular array, parallel to the length of the hair
  • Embedded with pigment granules that give hair its color
• Racial origin


  • Caucasian: Shaft diameter moderate with minimal variation, pigment granules sparse to moderately dense with fairly even distribution, cross-sectional shape oval
  • Negroid: Shaft diameter moderate to fine with considerable variation, pigment granules densely distributed and arranged in prominent clumps, shaft prominent twist and curl, cross-sectional shape flattened
• Body parts

  • Pubic hairs are short and curly with varying shaft diameter and continuous medulla
  • Beard is coarse and triangular in cross section with blunt tips acquired from cutting or shaving
• Forcibly removed hair

  • Suggests a violent confrontation
  • Presence of hair follicular tissue suggests hair has been pulled out quickly
• Infant hair


  • Fine, short and fine pigment
• Sex

  Male hair is generally larger in diameter, shorter in length, more wiry in texture than that of a female
• Environmental alterations

  • Can result from exposure to excessive sunlight, wind dryness, and other conditions
• Sources of collecting hair standards

  • Suspect
  • Suspect's clothing
  • Suspect's environment
  • Crime scene
  • Victim
  • Victim's clothing
  • Victim's environment
• Process of collecting hair standards

  1. Hairs should be pulled one at a time including the roots of the hair

  2. Place the hair in paper envelope and tape all the seams and label the container

  3. Head hair standards: 20 to 50 from various areas of the scalp

  4. Pubic hair standards: at least 20-25 by pulling individual hairs from various areas around the pubic region

  5. Facial hair standards: collect at least 20 by pulling individual hairs from various regions of the face
• Process of collecting questioned hair

  1. Pubic hair combings: usually collected in sexual assault cases and from homicide victims, place a piece of white paper under the pubic region and using a new comb, comb through the entire pubic area

  2. Other questioned hairs: place on a piece of white paper and carefully fold around the hair
• The test has value to exclude an individual if hairs were found different from the questioned sample
• Fiber


  The smallest unit of a textile material that has a length many times greater than its diameter, can occur naturally as plant and animal fibers or be man-made
• Fiber evidence


  • Can be transferred in manner similar to hair evidence
  • When matched to specific source, a value is placed on that association