midterm

• 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
• Semen composition


  • Prostate: milky substance full of enzymes, proteins, and minerals
  • Seminal vesicles: fructose and two-thirds of the fluid
  • Testicles: sperm and some other fluid
• Semen components


  • Seminal fluid/plasma (90%)
  • Formed cellular elements: Spermatozoa or sperm cells (10%), Epithelial cells (<1%), Crystals of choline and lecithin, Fructose, Acid phosphatase, Citric acid
• 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, Average volume per ejaculation is 2-5ml
• Hypospermia


  Less than 1.5ml
• Hyperspermia


  More than 5.5 ml
• Sperm cell parts

  Head, Midpiece, Tail
• Where semen can be found

  • Vaginal contents of the victim
  • Rectal contents of the victim
  • Pubic hair
  • Skin around the genitals
  • Underclothing
  • Bed clothing
• Physical examination of semen

  1. Microscopic examination - sperm cell stained and viewed under high power microscope

  2. Ultraviolet examination - seminal stains exhibit bright bluish fluorescence
• Chemical examination of semen

  1. Florence test - presence of spermatozoa confirms the presence of seminal stains

  2. Barberio's test - almost specific for human semen, seminal stain as old as 6 years respond

  3. Acid-phosphatase test - based on high acid phosphatase content of human male ejaculation
• Identification of spermatozoa is the only specific test for semen
• Visible result of semen tests

  • Florence test: crystals of choline periodide which are dark brown, rhombic or needle shaped
  • Barberio's test: crystals which are slender yellow-tinted, rhombic needles with obtuse angle or appear as ovoid crystals
  • Acid-phosphatase test: orange-red pigment
  • Spermatozoa: 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
• Trace Evidence: Number


  A series of number that is punched or pressed into a particular item to distinguished it from one another of common type. It's sometimes preceded interspersed with or followed by letters and symbols.
• Restoration


  The process of recovering or revealing an original serial number that has been tampered with or obliterated
• Serial Number


  A series of numbers that is punched or pressed into a particular item to distinguish it from one another of common type
• Macro-etching


  Application of chemical solution on the metal surface where the serial number is normally located and observing any reaction that may take place
• Purpose of Macro Etching

  • To determine whether or not the serial numbers of Motor Vehicles or Firearms are tampered.
  • To restore the original serial number of an article in questioned.
• Basic importance of number restoration

  • It establishes investigative lead from article/property that may have been taken from the scene of the crime
  • It proves that the property found in the possession of the suspect is actually owned by the victim
  • It resolves conflicting claims of property that has been recovered by the investigators
• Theories in Number Restoration

  • 1. When a letter or number is stamped into a cold metal surface a molecular disturbance occurs directly beneath.
  • 2. When a letter or number is punched into a metal, a deformation occurs on the metal surface that is the metal is being compressed.
• Preliminary Examination in Number Restoration

  1. A careful search for the location of the serial number must be made before attempting the restoration process.

  2. Grease and oil must be removed using gasoline, alcohol, etc.

  3. Clean or polish the area using sand paper.

  4. Photograph the affected area.
• Spot Detection of Tampered /Obliterated Serial Number

  • Presence of any sign of welding surrounding the serial number.
  • Presence of several scratches and filings marks on the serial number surface.
  • Presence of any sign of concavity on the serial number surface.
  • Presence of any difference in the style of letters and numbers.
  • Appearance of fragmentary marks which could not be properly identified partly superimposed by letters and numbers.
  • Presence of any difference in the spacing of individual letters and numbers.
  • Misalignment of letter and numbers.
  • Absence of one or more letters before, in-between or after a set of sequential numbers.
  • Letters and numbers are stamped on places where the serial number is normally located.
  • 10. Sizes of letters and numbers are sharper and coarser than the others.
  • 11. Presence of any irregularities in depth of individual letters and numbers.
  • 12. Absence of rating plate.
  • 13. Model of the vehicle in the chassis number does not tally with that of the rating plate.
  • 14. Alteration of the production number.
• Chemicals/reagents used


  • I. For Iron and Steel: Cupric Chloride + Hydrochloric Acid + water
  • II. For Aluminum: Nitric Acid + Water
  • III. For Lead: Glacial Acetic acid + Hydrogen peroxide
• Procedure on Macro-etching


  1. Examine the metal surface of a motor vehicle bearing the engine number to identify the type of metal where the engine number was stamped.

  2. Photograph the entire motor vehicle including the engine block. Make a close-up photograph of the metal surface where the serial number is normally located.

  3. Clean the surface and make it smooth using a sand paper. Remove the paint if the metal surface bearing the serial number is painted as in case of a chassis number.

  4. Get the stencil of the serial number by placing an onion paper over the numbers and applying repeated strokes of the pencil on the paper until all the letters and numbers are captured or by rubbing the serial number with carbon paper and then covering the area with plastic tape. Remove the plastic tape from the metal surface bearing the serial number and place it on bond paper.

  5. Apply melted paraffin wax around the area to be treated so that no spilling of reagent as well as no rusting action will take place after conducting the macro-etching examination.

  6. Using a cotton swab, apply a thin coating of Cupric chloride solution on the metal surface bearing the serial number through repeated strokes.

  7. Swab the metal surface with Nitric Acid repeatedly followed by the application of a mixture of 50% Cupric chloride and 50% Hydrochloric acid.

  8. Observe the etched surface for the appearance of letters or numbers, if there are any. Record and photograph any restored or partially restored letters and numbers.

  9. Wash the treated are with dilute ammonium hydroxide to neutralize the acid and then completely wash it with water.

  10. 10. Remove the melted paraffin wax around the metal surface right after washing it.
• Hair


  A slender, thread-like outgrowth from a follicle in the skin of mammals
• Hairs occur everywhere on the human body except on the palm of the hands and the sole of the feet
• Two kinds of Hair

  • Real Hair - generally long and stiff
  • Fuzz Hair - generally short, fine at times curly and wooly
• Parts of the Hair

  • Root - portion embedded in the skin
  • Shaft - portion above the surface of the skin. It is the most distinctive part of the hair.
  • Tip - sometimes termed point. The distal end of uncut hair shaft.
• Hair Root


  Responsible for hair production and growth
• Three development stage of hair growth

  1. Anagen (cyclical growth)

  2. Catagen (transition stage)

  3. Telogen (resting stage)
• Anagen phase


  • Lasts up to six years, the root is attached to the follicle for continued growth, giving the root bulb a flame-shaped. When pulled, anagen hairs contain follicular tag, a translucent tissue surrounding the hair shaft near the root.
• Catagen Phase


  • Hair continue to grow at decreasing rate which can last from two to three weeks. The root bulb shrinks in size and being pushed out from the follicle.
• Telogen Phase


  • Hair growth ends, the root takes on a club shaped appearance. During six to two months period, the hair will pushed out of the follicle causing the hair to be naturally shed.
• Stages of hair growth

  • Anagen
  • Catagen
  • Telogen
• Hair Shaft Components


  • Cuticle - protective coating made of overlapping scales
  • Medulla - central canal that may be empty or contain pigmented cells
  • Cortex - made of spindle-shaped cells aligned in a regular array, parallel to the length of the hair
• Cuticle


  • Has a characteristic pattern giving the hair resistance to chemical decomposition and retains its structural features over a long time. Not useful in individualizing human hair but can be used for species identification.

  
• Cuticle Scale Structures


  • Coronal (crown-like)
  • Spinous (petal-like)
  • Imbricate (flattened)
• 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 Classifications


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


  Measures diameter of medulla relative to the diameter of the hair shaft expressed in fraction. Human medullary index = less than 1/3, Animal medullary index = 1/2 or greater