FIS EXAM #4

Soil definition

earth materials

Soil Analysis

- Primary mineral in content
- Can only be individualized in unusual circumstances
- Often overlooked/undervalued
- Soil Is recognized as valuable evidence
- Most often used with shoe or tire print in the soil

Forensic Geologist are concerned with the \_______________ of soil particles from locations to objects and can the \_______________ be found

transfer; origin

What is the objective of forensic soil analysis?

Associate the soil found at a crime scene to its source (basically finding the origin)

What are the 4 compositions of soil? What are their percentages?

1. organic (5%)
2. inorganic (45%)
3. Water (25%)
4. air (25%)

organic soil components

- decayed and decaying plant and animal matter (called humus)

- makes up 5% of soil

Inorganic soil components

Crushed rock/clay, minerals, metals/nonmetals, crystalline solids

Soil Forensics

- Compare soil from the OG location to soil on the person.

- Measure chemical and physical properties to determine if the soil could have come from the same location.

Collection of Soil

- collect all layers of soil at once and intact.

- This can help establish the order of contact with soil. T

- a known and unknown sample are needed to compare

- Collect soil from multiple areas and depths

- Time of day

Do forensic geologists need known or unknown samples?

both

Issues when collecting soil

\- limited size, and amount \n - Contamination

Dry soil samples can be stored in \_________ (3)

plastic bags, film canisters, or airtight containers.

Wet soil samples should be stored in \______________ (2)

paper or cloth sacks

Both \__________ and \______________ analysis of soild can be used to compare 2 soil samples

physical and chemical

Where would a forensic geologist most likely work?

at a university

What must be done to the soil before analyzing it?

- Make sure the soil is representative (many times they are homogenized to ensure this happens). This is done by crushing and pulverizing

- This sets up the sample to be chemically analyzed

Analysis of Particle size of soil (physical examination)

- (first step)
- a sieves
- Each sieve level is analyzed individually

EX: mineral content

Analysis of Color of soil

\- certain soil has certain tints due to minerals present (Munsell color charts are used for this) \n \n - color effected by moisture, location, and minerals present \n \n - Colors can include light tan, white, or dark brown

Munsell Color Charts

standard color chart to keep color distributions consistent among scientists

Mineral Analysis of Soil

* done by looking at samples under a polarizing microscope
* look at the minerals present and the amount of that mineral present (calcium
* PH can help determine the minerals present because different minerals have a different PH

Physical Analysis of Soil includes....(4)

- particle size
- color
- Mineral Identification
- Rock Identification

Instrumental Analysis of Soil

- determine what elements make up the soil... USE SEM

- look at tiny particles
- % composition (GC)

HPLC UV Vis detector for Soil

- look at different leaves in the soil

IR for soil

- identify organic and inorganic components of the soil

Chemical Analysis of Soil includes.....(4)

SEM
HPLC
UV-VIS
IR

Florida v William Kennedy Smith

* Kennedy accused of Rape in FL
* Kennedy said they had sex on the beach. She said she was raped in the grass.
* Jay Siegal used PLM to compare samples from clothing of victims to lawn and beach areas
* Samples were consistent with the beach; not lawn. NOT convicted for rape.

South Dakota v Donald Eugene Moeller

Girl was murdered \n Soil showed someone lied about where they were at the time of the rape and murder \n Soil showed he was in the area \n Guilty; death penalty

Colorado v Walter Osborne

- Osborne brother kidnapped Adolph coors and killed him
- Body dumped at the top of a mountain peak
- Osborne burned his own personal car after dumping the body

The Death of a DEA Agent - Enrique Camarena

- Undercover agent murdered in Mexico
- soil on body was different from the soil he was buried in

What is the most common cases paint is used in?

automobiles (sometimes artwork)

Forensic term for paint

coating

Forensic Analysis of \__________ is one of the most complex areas in forensic labs.

coatings

Coating

covers any surface and is used to protect or make it look pretty, or provide a special quality (water proof)

What is paint?

\- a type of coating that is a suspension of pigments and additives intended to color or protect a surface

3 main components of paint

binder, pigments, vehicle/film former

3 Vehicle/film former components

binder, solvents, additives

pigment

a fine powder that is insoluble. Used to add color and can be organic or inorganic, or be a mixture

Binder

a portion of the coating that allows the pigments to be distributed across the surface.

vehicle/solvent

solvents, resins, and other additives that form a continuous film; this binds the pigment to the surface. \n \n This will eventually evaporate and leave a polymer behind.

stain definition

contains soluble dyes or a suspended pigment in a solvent

enamel definition

paint that dries to glass

clear coat definition

top/thin coat

Paint categories (4)

Architectural paint
Product Coating
Specialty purpose coatings
Art paint

Architectural Paints Definition and Examplesles

household paints found in houses or businesses
-Ex: wall paint

Product Coatng Definition and Examples

Applied in the process of manufacturing products

Ex: cars, appliances, colored objects

Special Purpose Coatings Definition and Examples

fulfill a specific need beyond protection or aesthetic improvement

Ex: waterproof/ fire resistance/ glow in the dark

Art Paint Definition and Examples

Used in paintings and are used to authenticate artwork or used in forgery cases

Automotive Finishes

automotive paint is one of the most commonly types of paint eviffence

How are cars painted? How many coats? What does each coat do?

4 coats of paint

Electrocoat (rustproof)

Primer (minimize corrosion)

Basecoat or Topcoat (gives the color of the car)

Clearcoat (acrylic protective layer)

How are cross-sections of paint observed?

micro scalpel tool (under steromicroscope)

Electrocoat Primer or Pretreatment

zinc electroplating and is applied to the steel body of the vehicle to inhibit rust

Car primer

usually an epoxy resin with corrosion-resistant pigments (car color)

Basecoat or Topcoat for car paint

may be in the form of a single-color layer coat, a multilayer coat or a metallic color coat

Clearcoats for car paint

unpigmented coatings applied to improve gloss and durability of a vehicle's coating

2 kinds of paint evidence

Paint Chips (flakes)

Smears

Paint chips (flakes)

- paint chips provide most important information from analysis as the layer structure is generally intact

Paint smears

 usually consist of top layer of paint, and are transferred (sideswipe)

a transfer of paint created when a painted object strikes a glancing blow to another object

Because of the variability of paint, it is important to collect known paint samples from________________________

near the point of damage or transfer

True or False?

Known samples should contain all layers of undamaged paint

True

True or False?

Subcoating surface should be included for analysis when possible

true

Collection of paint evidence

\- Collect paint from undamaged areas of car as near as possible to damaged area \n \n - Lifting loose flakes; cutting samples of paint \n \n - If possible, entire object should be removed and sent to lab \n \n - Paint evidence should be photographed and removed with non-metallic tools. Plastic is best

Can you use metal tools or tape lifts to remove paint?

NO; this could damage the paint layer

Paint generally is considered \__________________ evidence.

\_________________ matching of paint chips may be used

class \n \n Fracture

Most paint evidence is exclusionary - what does this mean?

it eliminates a source from the pool of suspects

Analysis of Paint - Physical Properties

- Paint layer sequence
- Thickness ratios of layers
- Color of layers

Analysis of Paint - Chemical Properties

- Solubility
- Components of paint chip
- spec

What spec tools are used for the entire paint chip?

What about for individual layers?

Entire paint chip: chromatography

Individual layers: Infrared microscopy

What of the first step to Analyze Paint Samples?

visual examination - stereomicroscope

Visual examination begins with looking for signs of potential \_________________ between submitted samples

cross-contamination

Things to note when looking at paint samples....

condition \n weathering characteristics \n size \n shape \n exterior colors and major layers present in each sample

a Combination of \_____________________________ are used to examine paint samples from 2x to 100x

stereo, transmitted light, and polarized light microscopes

What is a microtome?

a piece of scientific equipment used to hold something in place white it cuts things into very very thin slices.

Why are Solvent and Microchemical Tests used?

Used to discriminate between paint layers with different pigment and binder composition that are visually similar \n \n Paint, with different chemical compositions, will react differently \n \n Tests are destructive

\n Should be performed on known and questioned samples simultaneously

\n Helps classify paint

Instrumental Methods of Paint

- Microspectrophotometry (MSP)
- Infrared Spectroscopy (IR)
- Raman
- Pyrolysis - GC
- SEM/EDS

Microspectrophotometry

A technique for measuring, at various wavelengths, the quantity of light reflected or absorbed by a small object

IR on paints can identify what?

binders, pigments and additives used in paints and coating

Ramen Spec on paint is used for what?

look for polar binds and look at the clear coat layer... can also identify the binder

Why are paint sears hard to analyze and what is used to analyze it?

Analysis is difficult because multiple layers of paint can be difficult to distinguish


SEM/EDX may be best way to analyze the smear

Paint Data Query (PDQ)

\- International automobile paint database in Canada \n \n - Contains nearly 20, 000 samples of paint \n \n - Forensic Scientists enter the color, chemical composition, and layer sequence information from an unknown sample \n \n - Compare IR Spectra

Glass are most often characterized by what 3 things?

optical properties, physical properties, or by elemental content

Other names for glass (2)

crystal lattice or fluid

is glass an amorphous solid?

YES - this means it is disorganized and the molecular structure is not predictable.

What is glass made up of?

Largely made up of silicon oxides doped with other materials

How is glass made?

heating up sand and cooled without crystalizing \n \n Float glass: cooled on molten tin, which allows the glass to be very flat (Used in house windows)

Dopants Definition (glass)

alters the properties of basic silicon glas in a predictable way \n \n (MP, solubility) - dopants are often used in cookware

Glass may be strengthened by \___________.

tempering

How is glass tempering done?

- heated and cooled multiple times

Tempered glass

glass that is strengthened by introducing stress through rapid heating and cooling of the glass surfaces (car side windows, stairwell windows). Breaks into cubes.

Laminate Glass

two layers of glass with a layer of plastic in between to prevent shattering (windshields)

4 types of glass are encountered as evidence:

- sheet/flat glass
- container glass
- glass fibers
- optical glass (rare)

Why is it that most glass cannot be individualized?

\- Because of mass production, many types of glass do not possess any characteristics that can be used for individualization \n \n - small pieces of glass are class evidence

Even though it is rare.... glass can be individualized if a \___________________ occurs.

mechanical fit or fracture match

borosilicate glass is used in \___________

cookware

soda-lime glass

The most common type of glass. Used in a drinking glass or bottles or glass jars

float glass

flat window glass

\_______________ and \________________ analyses are used to characterize and compare glass that is too small to have a fracture match.

Other tests include.... (5)

Density and refractive index \n \n color, thickness, flatness, surface features, and fluorescence

bullet proof glass

multi-layer laminated glass (7 layers.... glass, plastic, glass, plastic, glass, plastics, glass... etc)

How can you determine if the material is actually glass.

Measure hardness, structure and behavior when exposed to polarized light

Preliminary tests for glass

color, surface characteristics, flatness, thickness, density, and fluorescence

True or false... different types of glass break differently.

TRUE