. Flashcards
Cordage terms that includes
- Cable
- Cord
- Linen
- Robe
- String
Made from twisted vegetable or synthetic fibers
cordage
pertains to small lines includes cord, twine , and string
Linen
Pertains to small tight lines:
- Cord
- Twine
- String
Heavier lines with 3 or more strands
Rope
Rope used in
- Suicide
- Robbery
Fibers combined and straightened by machine
Yarn
Drawn in parallel position and twisted together
Yarn
Single yarn of 2 -3 or more yarns twisted together
String or Twine
Thick String
Cord
Obtain from the last layer of the plant stem of dicotyledon plants
Soft Fibers
Soft Fibers are obtained from the last layer of the plant stem of
dicotyledon plants
Examples of soft fibers
-Cotton
-Flax
-Hemp
-Jute
Obtained from the structural system of the leaf of monocotyledon plants
Hard Fibers
Hard fibers are obtained from the structural system of the leaf of
monocotyledon plants
Examples of natural hard fibers
- Manila Hemp/ Abaca
-Sisal Hemp
-Coir
-New Zealand Hemp
Characteristic of Synthetic Fibers
- Strong and lighter
- More Flexible
- Greater resistance to chemical damage
- Do not rot
Examples of Synthetic FIbers
- Nylon
- Polyester
- Polypropylene
- Aramid
-Used in Parachute and glider rope.
-3x stringer than Manila Hemp
- Greater elasticity (anchor lines)
Nylon
Best rope for general use
Polyester
Polyester resist:
- Abrasion
- Sun’s UV
50% stronger than manila hemp
resistant to abrasion and UV from sun
Polypropylene
High melting point and resist stretching
Aramid
Jute comes from
Cochorus plants
From cochorus plants
98% produced by Pakistan & India
Blended with high fiber
Jute
2nd most important soft fiber
Hemp
A seed hair
Not deprived from barks of dicotyledon plants
Cotton
Most widely used in rope
Form leaf stem of abaca
Great strength and resistance to wind, sun, and rain
Manila Hemp / Abaca
-80% of the strength of abaca
- come from plant Agave sisalana
- Salt water resistant
- Tanzania, Kenya, Indonesia , Brazil, Haiti
Uses in rope twine for sacking soil and cable insulator
Sisal
Cordage Fiber Examination
I. Macroscopic
1. Length & diameter with Vernier Caliper
2. General Appearance
3. Stains, debris, direction of projecting surface fiber
4. Free ends
5. Knots
6. Adhering debris
Fiber Chemical Test may use of
- Phloroglucine
- Aniline Sulfate
- Iodine & Sulfuric Acid
is a representation of an impression made on a soil surface.
Moulage
A cast in Plaster of Paris or
other similar material of an object or its impressed outlines on a surface.
Moulage
Moulage several
importance:
a. Produce representation of an object
b. Great value in scientific criminal investigation
c. Create mold which photography may not become viable
any materials which can be changed from a plastic or liquid state to the
solid state
Casting Materials
The following are criteria for a good casting material
a. Must be fluid
b. Must harden rapidly
c. Must not be deformable
d. Must be tough
e. Must be easy to apply
f. Must not adhere to the material
g. Must have a fine composition
h. Must not injure the impression
i. Must be obtainable
j. Must be cheap
used for small impressions with a melting point at 60-70
degree Celsius but gives more accurate and detailed impression.
Wood’s Metal
A rubbery and gelatinous material which is made up of colloidal Mg soaps.When hot it is thin and pasty, while when cold it is stiff or jelly.
Negocoll
Made up of resinous material. Flesh in color and used for external surfaces.
Hominit
Brown in color and used to cast the human body
Celerit
Holds and keeps casting material from running
Molding Box
includes strip of metals, teased ropes and bamboo sticks
Reinforcements
used as separating materials
- Shellac and Alcohol
- Talcum powder
Casting Chemicals:
NaCl
Borax
Sucrose
NaHCO3
is detonated when it is crushed by the force of the firing pin
primer
These vapors recondense
into droplets, which are further subjected to high pressure and temperature arising from the
openings as vapors and solidified as particulate that varies in shape and size from submicron to over
100
microns
Components of Gunshot Residue
a. Formulation of Primer
b. Formulation of propellent
c. The barrel scrapings
d. The composition of projectile
Ammunition primers consists of four basic chemical components:
- The initiator
- The oxidizer
- The Fuel
- The sensitizing
is standard initiator in modern primer
The initiator – Lead styphnate
is most commonly used in small arms.
The oxidizer – Barium nitrate
Antimony sulfide is commonly used as fuel in primers
The Fuel
Commonly used sensitizers are tetracene, pentaerythritol tetranitrate and tetryl
The sensitizing
A black powder composed on 75% potassium nitrate, 15% sulfur and 10% charcoal
Gunpowder
Combustion product of black powder
Carbonomooxide
carbon dioxide
sulphates
carbonates
thiosulfate
sulphides and potassium
Can be single based made up of Nitrocellulose or Double base made up of
Mitrpcellulose and Nitroglycerine
Smokeless Powder
Detectable Inorganic components
Lead, Barium, Antimony, Copper from jacket of
bullet, Iron from barrel, Nitrates and nitrite, zinc
and nickel
Detectable Organic Components
Nitrocellulose, Nitroglycerine, Diphenylalamine
stabilizer, and DNT
The basic principle of trace and transfer evidence is the
Locard Exchange Principle
Detection of Gunshot residue
- Residue should initially be observed and evaluated by the unaided eye and with a low power
stereomicroscope - X-ray photography
- IR-photography-Infra red imaging may be used to visualize heavy soot on dark or bloody
clothing or on multicolored surfaces - Chemical methods
use 5% nitric acid for inorganic content
Wet Method
a technique used to inorganic sample for SEM analysis
Tape lifting
Most common technique that makes use of acetone of ethanol as solvents.
Most common technique that makes use of acetone of ethanol as solvents.
Swabbing
Used for collecting on clothing’s. Clothing debris are vacuumed on to a filter disc. Then using solvents, residue on filter paper will be
collected.
Vacuum lifting
Gunshot Residue Methods of Analysis
- Gross Examination
- Microscopic Examination
- Paraffin Test
- Walker’s Test
-Griess Test
- Non-conclusive
- Use of hand lens
- Check for fine black powder particles:
-Entrance of gunshot
- Dorsum of hand
Gross Examination
- Fine particles magnified
- No characteristic shape, color or consistency of gunpowder
Microscopic Examination
- Diphenylamine Test
- Dermal Nitrate Test
- Lunge Test/ Gonzales Test
Paraffin Test
Uses photographic paper treated with either: C-Acid (2-naphthalamine- 4,8-
disulfonic acid), H- Acid (1-amino-8-naphthol-3,6-disulfonic acid) or Sulfonic Acid
swabbed with alpha naphthalamine in ethyl alcohol
Walker’s Test
Uses photographic paper treated with either: C-Acid (2-naphthalamine- 4,8-
disulfonic acid), H- Acid (1-amino-8-naphthol-3,6-disulfonic acid) or Sulfonic Acid
swabbed with alpha naphthalamine in ethyl alcohol
Walker’s Test
Principle: Nitrates in the gunpowder residue (NO3) reacts with the diphenylamine
Paraffin Test
Principle: Nitrite in acid solution reacts with a primary aromatic amine forming diazonium salt
Griess Test
Principle: Nitrite in acid solution reacts with a primary aromatic amine forming diazonium salt
Griess Test
Test for Primer components
Sb.,Ba.,Pb.
Swab moistened with 0.1M HCl gathers residues
Harrison & Gilroy Test
Ba and Sb converted to isotopes by neutron bombardment
Neutron Activation
Analysis (NAA)
High temperature vaporizes metallic elements
Detected through Absorption Spectrophotometry
Flameless Atomic
Absorption
Tests for Primer Components
-Harrison & Gilroy Test
-Neutron Activation
Analysis (NAA)
-Flameless Atomic
Absorption
Methods of Glass Analysis
- Spectrograph
- X-ray analysis
- Physical properties
- UV Examination
The only adequate method for chemical analysis
Not rapid method
Spectrograph
Study of diffraction pattern
X-ray analysis
Most sensitive method in determining differences
in composition of glass
Physical properties
Examined in a dark room A difference in fluorescence
is indicative of physical and chemical differences
UV Examination
Glass as evidence in Crime, Forensic chemistry application:
a. Automobile glass in cases of hit and run
b. Broken windows caused by pressure, blow or bullets
2 Kinds of Glass Fractures
- Radial Fractures
- Concentric Fractures
Primary fractures
Resemble spokes of wheel
Radiating outward from the point of impact
Radial Fractures
Secondary Fractures
Circles around the point of impact
Connecting to one radiating crack to others
Concentric Fractures
When a force pushes on one side of a plane of glass,
the elasticity of glass permits it to bend in the direction of the
force applied. Once the elastic limit is exceeded,
the glass begins to crack.
Breaking of Glass
Radial cracks form a Right angle on the Reverse side of the force. Radial cracks are first
commencing on the side of the glass opposite to the destructive force. Stress lines on a concentric crack
will be at right angles to the front. Concentric cracks occur afterwards. Starting on the same side as the
line force.
3 R’s Rule