1985 Alec Jefferys at Leicester University
DNA
Chromosomes
DNA - deoxyribonucleic acid
Nucleotides -
    1.sugar deoxyribose
    2.phosphate
    3.base
Double helix
    Base pair matching only adenine to thymine and guanine to cytosine
    Instructions for linking amino acids into the proteins of the body and its functions through enzymes
    DNA naturally duplicates itself during mitosis and meiosis
    Restriction fragment length polymorphisms
    Not part of the instructions - nonsense
    Numerous possibilities for repeating sequences.
    Look for differing lengths of repeating sequences

RESTRICTION FRAGMENT LENGTH POLYMORPHISMS
electrophoresis plate

SOUTHERN BLOTTING transfer process
RADIOACTIVELY LABELED COMPLEMENTARY DNA FRAGMENTS OF THE SAME SEQUENCE
hybridization
photographic film
USING JUST 4 DIFFERENT PROBES WOULD GIVE A PROBABILITY OF DUPLICATION OF ONE IN A HUNDRED MILLION.

POLYMERASE CHAIN REACTION
very small amounts of DNA from a pulled hair, a blood stain
G T C T C C T T C C A G
C A G A G G A A G G T C
heating to 94 degrees C.
add primers - DNA with specific base sequences
lower the temperature and  primers hybridize - prevents the DNA segments from recombining with separated portions.
add the DNA polymerase - recombines the DNA into double strands
Add the free nucleotides
free nucleotides to line up along the strand of DNA duplicating it
Repeat the cycle 25 to 30 times will yield a million copies of a DNA fragment

FINGER PRINTING FOR FORENSIC WORK
uses the HLA DQ alpha system.
distinguish 21 different types.
routinely add 5 other genetic markers and in combination with HLA DQ produce frequencies of occurrences less than 1/1000
tests excellent at showing suspect is not the source of the DNA - if do not match they do not match
if do match there is a 1 in 21 chance it is not his or her DNA.

Forensic Scientist - detect and identify relevant chemical materials collected at scene and reconstruct and identify igniters and detonating mechanisms.

OXIDATION - COMBINING OXYGEN WITH OTHER MATERIALS TO PRODUCE NEW MATERIAL

CH4     +   2O2     YIELDS        CO2      +  2H2O  +  ENERGY
METHANE +  OXYGEN     =      CARBON DIOXIDE + WATER +  ENERGY

Energy needed to begin oxidation is ignition temperature
solids only in vapor form
Flash point lowest temperature a  liquid has sufficient vapor to form a volatile mixture of vapor and air
  Flash point of gasoline is -50 degrees centigrade
  high ignition temperatures
  Gasoline is 495 degrees centigrade
Solids cannot burn until in vapor form

PYROLYSIS.
Explosives have own sources of  oxygen mixed in with them

Black powder:
75% POTASSIUM NITRATE (KNO3)
15% CHARCOAL (C)
10% SULPHUR (S)

AT IGNITION THIS MIXTURE PRODUCES CARBON DIOXIDE (3CO2), NITROGEN (N), POTASSIUM SULFIDE (K2S) AND LARGE AMOUNTS OF HEAT.

SEARCHING THE FIRE SCENE:
evaporate within hours immediate investigation of the fire takes precedence
Search of the fire scene must focus on finding the origin of the fire
SNIFFER  - rapid screening for combustibles
       Sucked into machine, passed over heated element, if vapor present will oxidize, raises temperature of filament, and     registered on the meter.
2 to 3 quarts of ash and debris.
sealable container
  New paint cans
  mason jars
collect control materials and any containers
collect the clothing of suspect

LABORATORY
heated and the vapor withdrawn with a syringe
VAPOR CONCENTRATOR -
charcoal-coated Teflon
Place in container
Heat to 60 degrees C for an hour
washing with a solvent - carbon disulfide.
GAS CHROMATOGRAPH

EXPLOSIVES
combustion - but very rapid
mixed with it the source of oxygen
rapidly moving wall of expanding gas

LOW EXPLOSIVES
Lower speed of detonation.
Black powder mixture of potassium nitrate, charcoal, and sulfur.  Smokeless powder is nitrated cotton/nitrocellulose or in the double base form nitroglycerin mixed with nitrocellulose.

HIGH EXPLOSIVES
1. INITIATING EXPLOSIVES OR PRIMERS
lead azide, lead styphnate, and mercury fulminate
2. NONINITIATING EXPLOSIVES
dynamite - nitroglycerin absorbed in a pulp matrix; has sodium nitrate added as an oxygen source to provide for complete combustion.

TNT - trinitrotoluene
PETN - pentaerythritol tetranitrate
RDX  - cyclotrimethylenetrinitramine
tetryl - 2,4,6-trinitrophenylmethylnitramine
Also the ammonium nitrate and sodium nitrate mixtures gelled with a natural polysaccharide such as guar gum
 ANFO is ammonium nitrate soaked in fuel oil

EVIDENCE COLLECTION AND ANALYSIS
blast crater
paint cans and mason jars.
1. Examine all debris with stereomicroscope looking for fragments of the bomb, primer, and uncombusted blasting material.
smokeless and black powder characteristic shapes.

2. Rinse in acetone
   rinse with water water soluble components such as the nitrates and chlorates.
3. Chose the testing procedure.
   Color tests:
        1.Griess
        2.Diphenylamine
        3.Alcoholic KOH
Confirmation:
Thin layer chromatography
High performance liquid chromatography - test of choice as it operates at room temperature and will not cause the explosive to decompose
Infrared spectrophotometry discussed during drugs
X-ray diffraction  discussed during soils

1903 Will West arrived at Fort Leavenworth Prison

William Herschel,  English civil servant in India late 1800's used to seal legal documents.

Henry Fauld, Scottish physician

Japan published in 1880 to identify criminals.

Francis Galton, English anatomist 1892  published Finger Prints

Juan Vucetich, Argentinean police officer---system of classification in 1891

Sir Edward Richard Henry an Englishman in 1897--classification system based on Galton's work
First use in US was the New York City Civil Service Commission in 1901.

1924 finger print collections of Leavenworth Prison and Bureau of Investigation combined into the records of the FBI
largest finger print collection in the world.

FINGER PRINTS
    1.friction ridges
    2.interface of the dermis and epidermis is a layer of cells called the dermal papillae.
    3.The topography of this layer determines the shape of the friction ridges
    4.sweat and any oil picked up from touching other parts of the body which remain behind on a touched surface leaving the pattern behind of the ridges and known as a latent finger print.

Finger print pattern:
LOOPS -
        Loop is surrounded by 2 diverging lines known as type lines.
        Ridge point nearest the two type lines is the delta.
        The core of the looping lines is the line in the most center point with tightest loop.
        All loops have one delta.
    Ulnar Loop opens to the ulna bone under the little finger.
    Radial Loop opens to the radius bone under the thumb.
WHORLS-
        all whorls have two deltas.
    Plain Whorl - if line drawn between the two deltas touches any one of the spiral ridges it is a plain whorl.
    Central Pocket Loop - if line drawn between the two deltas does not touch a spiral ridge it is a central pocket loop.
    Double Loop - two loops combined into one print.
ACCIDENTAL
    Any pattern not a plain arch which does not fit or a combination of 2 or more patterns of loops and whorls and arches.
ARCHES
    Ridges entering from one side of print and exiting on the other with none making a circle.
        Plain Arch--Simple arch pattern.
        Tented Arch---When there is a sharp spike or vertical line in the center of the arch.
                                 Ridge characteristics or minutiae:

PRIMARY CLASSIFICATION SYSTEM
FBI system based on all ten finger prints
1024 groups.
presence or absence of a whorl pattern

R. Index    R. Ring     L. Thumb   L. Middle    L. Little
________    _________   ________   _________    _________
R. Thumb    R. Middle   R. Little  L. Index     L. Ring
 

16 +  0  +  0  +  0  +  0  +  1   17
_______________________________  =__
 0 +  8  +  0  +  0  +  0  +  1    9
 

Computer technology

DETECTING PRINTS AT CRIME SCENE
Visible prints -
Plastic prints -
Latent prints - are invisible and are the leaving of the sweat and oils on a surface
visualized
finger print powder
dusted with powder
photographed
photographed and mapped with the location marked.
print is lifted clear plastic sticky film, then laid down on a labeled card of suitable color contrast

DETECTING PRINTS AT LABORATORY
Iodine fuming  ---Not permanent.  Photograph immediately.
                            Preserved with 1% solution of starch and water - turns blue
Ninhydrin (triketohydrindene hydrate) sprayed on surface, reacts with amino acids left from sweat and oil, turns purple blue.  as old as 15 years.

Silver Nitrate - reacts with salt
exposed to UV light - sun light - silver chloride turns into silver - dark.
should be in following order - iodine, ninhydrin, silver nitrate slide
Super Glue Fuming
-cyanoacrylate ester -
vaporized by heating in closed chamber
Alternate light sources -
lasers and variable light wave generators.
fluoresce upon exposure to laser light or
specific wave lengths of light

GOAL: to determine if a firearm caused the wound or damage to property, matching the projectile or cartridge to the weapon, and reconstructing the circumstances of the wound or damage
BULLET COMPARISONS
    caliber - hundredths of inches or in millimeters
    Shotguns are measured in gages - 10, 12, 16
Rifled
lands - thus pattern is of lands and grooves
vary in number and in the direction of rotation
steel hock cutters  - before 1940
broach cutter
button or steel plug
pattern of lands and grooves
which firearm type or manufacturer made the gun
General Rifling Characteristics File
microimperfections
CARTRIDGE CASES
firing pin leaves an impression in the soft metal of the primer which varies in position, shape, and striation pattern.  In addition there are the marks made as the cartridge is pressed against the breach during firing and the tool marks of the extracting mechanism.
COMPARISONS
The weapon must be obtained.
tank of water so the projectile is not deformed.
comparison microscope
detailed measurements
GUNPOWDER RESIDUES
reconstruct the circumstances of the incident:  how far away was the gun fired?  was it a suicide or murder?  who fired the shot?
hot gasses generated by the exploding powder or nitrocellulose.  same type of ammunition
target is similar to the clothing or other material to be studied 1. if weapon is in contact to 1 inch from the target a heavy concentration of smokelike vaporous lead surrounds the bullet hole.  Often the lose fibers around the hole are scorched.  Blowback of the hot gases may produce stellate tears around the hole.
2.  Halo of vaporous lead around the hole indicates distance of 18 inches or less.
3.  Scattered specks of unburned and partially burned powder grains without any soot indicates distances up to 25 inches.
4.  Beyond 3 feet there will be now deposits except the bullet  wipe of the bullets passage around the hole.
color contrast is such that reside is not observed on the cloth - here infrared light and photography can reveal the presence of these deposits.

Nitrates - incomplete combustion of nitrocellulose powder can be found by ironing onto the cloth a chemically treated gelatin coated photographic paper.  The photographic paper is developed and the residue will be revealed and the pattern visualized.

Primer residues on hands
1. Old method paint on melted wax (the paraffin test), let harden and treat the removed surface with diphenylamine.  Blue color indicates nitrates - unfortunately nitrates also found in fertilizer, urine, cosmetics, tobacco.  Now have specially designed kits with special paper with adhesives and the chemicals for the tests available on site.
2.  With exception of 22 primers are a blend of lead styphnate, barium nitrate, and antimony sulfide.  Wipe the hands with swab moistened with 5% nitric acid.  Then forward the swabs to lab for testing for barium and antimony using any variety of techniques.
Then test for these substances with flameless spectroscopy or neutron activation.

NEUTRON ACTIVATION
nondestructive
test simultaneously for 20-30 elements
Bombard with neutrons in a nuclear reactor
neutron captured by an atom - new isotope
begin to decompose
Gamma rays are emitted
energy level of the gamma rays are characteristic of each element intensity of the gamma rays can be used to identify the concentration or quantity of the element.

MICROPROBE - SCANNING ELECTRON MICROSCOPE
look for particles with SEM once particles are located use the microprobe to see if it contains barium and antimony.

OBTAIN THE TOOL(S) USED - BEST IN POSSESSION OF SUSPECT
Replicate
MARKS MADE AT CRIME SCENE COMPARED TO MARKS MADE BY TOOL IN THE LABORATORY USING THE COMPARISON MICROSCOPE

RESTORING SERIAL NUMBERS AND OTHER MARKINGS
alter the crystal structure of the metal for a considerable distance below the surface
distorted crystals are dissolved by acids faster then the surrounding undistorted metal
Polish surface
Etch with acid

PRINTS AND MARKS
Remove the entire print
Overall photo and map.  Close up photos with scale, direct on and side lighted.
CAST IN PLASTER IN DIRT AND SOIL - DENTAL STONE AND MOLD
Dust and dirt - large sticky paper made for hand prints.
Snow-Print - spray on wax
test-control print of own shoe in same material to test technique and to verify that a match can be done.
Louise Robbins (1986, JFSCA 31:143-152) has developed formulae for estimating stature and weight

HANDWRITING COMPARISONS
    1.Vary in angularity, slope, speed, pressure, letter and word spacing, dimensions of letters, connections, pen movement, writing skill, finger dexterity.
    2.Comparisons of known writing, authenticated with questioned.  Hand writing exemplars - collected under controlled conditions, given similar pens and paper, collect several pages of repeated dictated text same as or containing same words as the text to be compared.
TYPEWRITING COMPARISONS
    1.Identification of the manufacturer and model of a given typewriter
    2.Vertical and horizontal alignment, perpendicular alignment, defects in the individual letter faces.
    3.Condition of the ribbon, examples of each touch or pressure control, examples of different number of pages typed on.
ALTERED DOCUMENTS
    1.Mechanical erasure - rubber eraser, sandpaper, razor blade, knife disturb the fibers of the document which can be revealed with microscopic examination.
    2.Strong oxidizing chemicals
    3.Infrared light
    4.Absorb infrared light.
    5.Ultraviolet
    6. blue-green light with absorb the radiation and reradiate infrared light.
    7.Infrared Luminescence.
DIGITAL PHOTOGRAPHIC ENHANCEMENT
INDENTED WRITING
Can be revealed by oblique lighting
Electrostatic charge on polymer film in close contact with sheet with indented writing.  Using copy machine toner spread on the polymer sheet can reveal writing
CHEMICAL ANALYSIS
Inks can vary in the combinations of dyes
1968 U.S. Treasury Department library of chromatographs of commercial pen inks.