Body Measurements to Distinguish Between People

Historical development
Scientists
Bertillon’s anthropometry
Body measurements to distinguish between people

Galton’s distinctiveness of fingerprints
Lattes categorized ABO blood groups
Goddard determined if bullet fired by a particular gun

FBI under Hoover made large-scale effort in forensics
Extend to state and local authorities

Crime laboratory
Basic services
Physical science unit
Uses chemistry, physics and geology
Identify drugs
Soil and mineral analyses
Examine trace physical evidence
Biological unit
DNA analysis
Blood and body fluid identification
Comparison of hairs and fibers
Botanical comparisons
Firearms unit
Examine guns, previously-fired bullets, cartridge cases, shells and ammunition
Clothes and objects examined to determine type of gun and position of shooter
Photography unit
Examines and records physical evidence
Digital imaging
Infrared, X-ray, ultraviolet photography
Create exhibits for courtrooms
Full-service
Toxicology unit
Study body fluids and organs to determine presence or absence of drugs
Ex. Blood-alcohol
Latent fingerprinting
Hidden fingerprint analyses
Polygraph unit
Voiceprint analyses
Use sound spectrograph to identify voices
Evidence-collection unit
Protect and preserve evidence from crime scene
Other forensic services
Forensic pathology
Investigation of sudden, violent or unexplained deaths
Usually a coroner
Questions sought to answer:
Who is victim
What injuries are present
When did the injuries occur
Why and how were the injuries produced
Autopsy to establish cause of death
Classification of deaths
Natural
Homicide
Suicide
Accident
Undetermined
Estimating time of death
Rigor mortis
Within 24 hours but gone after 36 hours
Muscles become rigid
Livor mortis
Settling of blood to parts closest to ground
Can be used to see if body has been moved
Algor mortis
Body temperature cools 1 to 11/20 F per

hour

Potassium levels in ocular fluid
Cells within eye release Potassium after

death

Forensic anthropology
Examination of human skeletal remains
Determine age, approximate age, sex, race, skeletal injury
Forensic entomology
Can be used to estimate time of death
Forensic psychiatry
Human behavior and legal proceedings are examined
See if people are competent to stand trial or make a will
Develop profiles of criminals
Forensic engineering
Fires, explosions, structural failures, accidents

Court cases involving use of forensics in judicial proceedings
Frye v. United States
Decision of admission of procedures, techniques and principles depends on its general acceptance by a “meaningful segment” of the scientific community
Daubert v. Merrell Dow Pharmaceutical, Inc
Frye standard not absolute and evidence can be admitted even if not general acceptance by a “meaningful segment” of the scientific community
Made trial judges responsible for determining acceptance
Guidelines
Scientific technique or theory can be tested
If it has been subject to peer review
Its potential rate of error
Standards controlling the technique’s operation
Widespread acceptance in scientific community
Allows for admission of new techniques unique to solving new problems
Processing the crime scene
Physical evidence
All objects that a crime has been committed
All objects that provide link between crime and victim
All objects that provide link between crime and its perpetrator
Securing crime scene
First officer that arrives must secure scene
Lead investigator will develop plan to document scene
Photograph evidence while it is unaltered
If objects moved then pictures may not be admitted as evidence
If moved must be noted in report
Pictures of entire scene including points of exit and entry
Surrounding areas where important events occurred before or after crime
If indoors all wall areas photographed and adjacent rooms
If body then photos of body position and location relative to entire scene
Close-ups to show injuries and weapons
Surface beneath body after it has been removed
Each item at scene is photographed to show position relative to entire scene
Then close-ups to show details of itself
Include ruler or something to show size
Videotaping where one records and one narrates as go through area
Note: photography shows detail better than video
Sketches
Rough sketch shows dimensions of scene and location of all objects
Create a legend
Objects are located by two fixed points like walls
Compass pointing north
Finished sketch is prepared with craftsman’s tools
Notes
Detailed description of scene with location of physical evidence found
Must be detailed because coming back to it in months or years
Record time evidence found and by whom
Also need who and how it was packed and marked by
Tape recording can also be useful
Video allows for photo and notes at once but must be transcribed eventually

Systematic searches
Need to be done so that no accusations of cover up arise or overlook of evidence is incompetence
Need one person in control to coordinate collection of evidence in searches
Spiral, line, grid or quadrant searches may be employed
Many items are microscopic or undetectable at scene
Ex. Hair, blood, fibers from clothes
May need a broom or special vacuum to use under the microscope
Collecting clothing of suspect should be dome
Scraping under finger nail with toothpick of suspect
Victim’s autopsy: material sent to lab
Clothing
Fingernail scrapings
Hairs
Blood
Vaginal, anal, oral swabs for sex linked crimes
Bullets from body
Collecting and packaging evidence
Purpose is to prevent any changes between time it was removed and time received at lab
Nothing should be tampered with until it reaches lab
Ex. Not pulling hair off of clothes
Pill bottles are good for storing small objects
Manila envelopes are also good
Clothes must be air dried and stored individually in a paper bag
Stops mold and mildew from ruining evidence
Maintain chain of custody
Scene, transport, lab
Sign out if removed
Controls
Hair at scene and hair from suspect
Crime scene safety
AIDS and hepatitis B from body fluids
Officers with contact must have had a hepatitis vaccination
Legality
Can’t search unless a probable cause
Exceptions:
Emergency situation
Need to prevent immediate loss of evidence
If made with a lawful arrest
Consent of all parties

Physical evidence
Types of physical evidence
Blood, semen, saliva
Documents
Drugs
Explosives
Fibers
Fingerprints
Firearms and ammunition
Glass
Impressions
Organs and physiological fluids
Paint
Petroleum products
Plastic bags
Plastic, rubber
Powder residues
Serial numbers
Soil and minerals
Tool marks
Vehicle lights
Wood and other vegetative matter
Identification
Determine what type of chemical or substance
Ex. Type of drugs, explosives, or species of a hair
Steps involved
Design systematic analysis that will always test for that substance
Testing must eliminate all other possibilities
Some substances require 1 to 10 tests
Comparison
Attempts to establish if two or more objects have a common origin
Select properties from suspect and control specimens
Give conclusions as probability
Two types of characteristics
Individual characteristics are substances that are related at almost 100% probability
Fingerprints are 1 X 1060 that two people are same
Class characteristics
Substance can be associated with a group but not

individual source

Ex. Blood types
Can use additional factors in blood
At crime scene, a lot of these can identify

suspect

Crime scene reconstruction
Outline of a likely sequence of events
Done by physical evidence, observations and statements
Need medical examiners, forensic scientists and officers
Steps to reconstruct
Secure scene
Preliminary examination of scene
Develop hypothesis using naked eye to piece events

together

Develop “attack plan” to search the crime scene

Go through scene for physical evidence

Physical versus chemical properties
Physical describes substance without reference to other substances
Ex. Mass, density, color
Chemical describes behavior of substance when it reacts or combines with another substance
Ex. Wood burning, Marquis reagent and heroin
Properties are usually related to metric system
1 Liter = 1,000 cubic centimeters (cc)
Or 1 ml = 1cc
Metric to English conversions, vice versa
Physical properties
Temperature
Melting, boiling, freezing points
0F, 0C, OK
Weight and mass
Weight versus mass
W = mg
Density
D = M/V
Independent of size of material
Methods to measure volume
Must note temperature of gas and liquid because density changes with temperature
Solid more dense than liquid than gas

Physical properties of glass
Refractive index
Light slows when it hits another medium
Decrease in speed causes light to bend (refraction)
Ex. Object at bottom of pool
Refraction index is ratio of speed of light in vacuum to its speed in another medium
Refractive index = velocity of light in vacuum/ velocity in medium
Water at 250C index = 1.333 times faster in vacuum
Means 1.333 times faster in vacuum
Dependent on temperature and the frequency of the wavelength of light
Use standard wavelength called the sodium D light
Transparent solid will “disappear” if placed in a liquid with similar refractive index
Amorphous solids have atoms arranged randomly so have one refractive index
Crystalline solids have atoms arranged in orderly manner so have two indexes
Known as double refraction
Calcite can be placed on writing and see two of each letter
One index is 1.486 and other is 1.658
Difference is known as birefringence
Birefringence is .172
Used to classify crystals
Dispersion is process of separating light into its colors (wavelengths)
Prism
Comparing glass fragments
Can be used to place a suspect at the crime scene
Structure of glass
Amorphous solid
Composed of silicon oxides mixed with various metal oxides
Glass made when sand is mixed with metal oxides

and melted and cooled

Soda added to lower sands melting point and viscosity
Lime is added so the glass will not dissolve in water
Soda-lime glass
Addition of metal oxides such as sodium, calcium, magnesium and aluminum

Borosilicates use Boron oxide to make glass such as Pyrex
Tempered glass made by adding stress from rapid heating and cooling
It breaks instead of shatters
Used in cars
Laminated glass contains a piece of plastic between two pieces of ordinary glass

Matching glass fragments
Suspect and crime scene fragments fit together means statistically impossible not to be from same source
Much of glass is usually to fragmented to match
Density and refractive index are best properties to examine
These properties are class characteristics
Density can be measured by using the flotation method
Control glass added to liquid
Density of liquid adjusted until control glass

suspended

Unknown is then added to see if it floats or sinks

Refractive index determined by immersion method
Glass put into liquid
Refractive index of liquid adjusted by temperature

until a match point is reached

Point when Becke line disappears because both liquid and glass have same refractive index

Hot stage or GRIM 2 used

If density and refractive values different from suspect and scene than not from same source
If same still can’t identify it from one source
Must compare results with frequency of occurrence of glass in society
Scientist can make a meaningful assessment as to

probability that the fragments were at one time from

one source

Tempered versus non-tempered glass
Determined by process called annealing
Involves slowly heating then cooling glass
Change in refractive index for tempered is much

greater than non-tempered

Glass fractures
Glass bends when force exerted
If force greater than glass’s elasticity, it fractures
Penetration of glass leaves typical fracture patterns
Radial fractures
Concentric fractures
Size and shape of hole can’t be sole factor of projectile
Ex. Small stone throw hard enough leaves similar hole as bullet
Large stone shatters window just like a gun at close range
Gun powder left behind id it is a gun
Hole from projectile can determine direction it came from
Hole is wider at exit side
As velocity of bullet decreases the irregularity of shape and surrounding cracks increase
Formation of radial lines
Form on opposite side of penetrating force
SEE TOM
Collection and preservation of glass evidence
All glass must be found to increase odds of matching pieces together from suspect and crime scene
Must submit all glass samples found on suspect and a sample of broken glass (control glass) from crime scene
Control glass should be taken from area closest to point of breakage
Glass should be placed in solid containers to avoid further breakage
Individually wrap each garment from suspect. Glass should not be removed from these

Physical properties of soil
Soil characteristics
Any natural or unnatural item found on or near Earth’s surface
Ex. Rocks, minerals, vegetation, glass, paint chips, etc…
Can link suspect to crime scene based on its transferability
Comparison of soil can begin with simple observation
Color can be used only if samples are dry
Microscopes allow to see plant and animal remains
Minerals can be identified along with their concentrations
Mineral is a naturally occurring crystal with definitive physical properties
Rocks and minerals used as building materials so can compare these pieces also
Density-gradient tube is used to determine density distribution of soil
Clear tube is filled with liquids of various densities
Soil texture can be used to determine type of soil
Collecting and preserving soil evidence
Samples taken at crime scene and at intervals within a 100 yard radius
Establishes variation of soil at scene
Samples should also be collected at all of suspect’s alibi places
These samples should only include top soil layer because it is only part transported
Should be packed in plastic vials and marked to location
Garments with soil should be individually wrapped in paper bags
Clumps of soil should not be broken up
Analysis of organic compounds
Matter is anything that has mass and occupies space
Element is simplest substance that provides building blocks that compose matter
Smallest particle of element and has its property is the atom
Compound is two elements joined
Molecule is smallest unit of a compound
Ex. one molecule of the compound CO2
Physical states of matter
Relationship to volume and shape
Conversion into various states
Sublimation
Organic versus inorganic
Selecting analytical technique
First if organic or inorganic
Qualitative versus quantitative determination
Former seeks to identify material only
Second seeks to find % combination of components of mixture
Chromatography is separation and analyses of mixtures of chemical substances
Occurs due to the observation that substances partially escape into environment when dissolved in a liquid or when absorbed on a solid surface
Dissolved gas molecules in a liquid will leave and reenter liquid into equilibrium is reached.
The higher the solubility of gas in liquid, the more molecules that stay in solution
Requires a stationary phase and moving phase in contact with one another
If moving air is in contact with stationary water, then gas out of liquid will be pushed along
Gas with high solubility will take longer to move
Allows for identification based on retention time
Gas chromatography (GC)
Separates mixtures based on a stationary liquid phase and a moving gas phase
Works well on highly complex mixtures
Allow for identification and quantification of each compound
Design of procedure
Carrier gas moves through column at a constant rate
Gas must be inert so it does not react with mixture
Mixture injected as liquid into heated port to vaporize it
This vaporized material is swept through column by carrier gas
Column is filled with a liquid
Column is continuously heated to keep it as a gas
Substances in mixture with high affinity for liquid phase will be slow, vice versa
Long column allows for a complete separation of mixture
Each component enters a detector as it emerged from column
Records its retention time on a chromatogram
Compared to a standard to determine type
Pyrolysis gas chromatography is used for substances that can’t be directly injected into GC chamber
These materials are heated to high temperature so they decompose into numerous gaseous products
Then the gas is injected into column
High-performance liquid chromatography (HPLC)
Advantage is that it can be done at room temperature
Moving phase is liquid and stationary is fine solid particles
Liquid carries unknown mixture over particles
Substances are slowed as it interacts with particles
Allows for identification based on retention time
Thin-layer chromatography (TLC)
Solid stationary phase and a liquid moving phase
Sample must be a liquid or solid dissolved in a liquid
Liquid moves up column picking up unknown mixture
Compounds that have high affinity for solid do not move as far
The paper is removed and allowed to dry
Finding the various compounds requires fluorescence
Need an ultraviolet light
Finding can also be done by spraying chemical on paper to cause compounds to generate colored spots
Identification of compounds is then done by comparing it to known sample

Electrophoresis
Separates protein and DNA based on their sizes and charges
Done by placing samples into wells of a solid gel
Opposite charges at each side cause sample to move
Properties of light
Electromagnetic spectrum components can be distinguished by wavelengths or frequencies
Objects have color due to absorption and reflection of various wavelengths of light
Light acts as a wave
Wave can be measured by wavelengths (trough to trough)
Measured by frequency (number of crests passing given point in a set time)
Light acts as a photon
Higher frequency means more energy
More energy means more dangerous for humans
Spectrophotometry
Measures the amount of radiation a material absorbs
Dependent on frequency or wavelength of radiation
Material can be quantified because the more material the more radiation it will absorb
Spectrophotometer
Graphs results in form called absorption spectrum
Radiation source
Monochromator selects single wavelength
Holder for sample
Detector measures unabsorbed radiation
Graph to make absorption spectrum
Use of UV as radiation source produces an absorption spectrum that usually can’t ultimately distinguish it
Use of infrared produces a complex pattern that can be used as a chemical’s fingerprint
Mass spectrometry
Coupled with GC to specifically identify a substance
Each gas component coming from GC passes into spectrometer
Inside it is collided with electrons
The collision causes materials to lose electrons and ultimately become unstable
This leads to molecular break down
Each of these smaller fragments can be separated by mass by going through a magnetic field
No two substances produce same fragmentation pattern

Analysis of inorganic compounds
Inorganic analyses is used to identify explosives, paints, metals, etc…
Analyses can identify if two or more objects come from a similar source
Manufactured goods require raw materials from Earth’s crust
Crust contains various trace elements or impurities at certain locations
Emission spectrum of elements
Elements can absorb and emit wavelengths of light
Allow for emission spectroscopy and atomic absorption spectrophotometry
Emission spectrum is the light emitted from a source and is separated into its colors or frequencies
Light from sun or incandescent bulb has an emission spectrum that is continuous
Elements produce discontinuous or line spectrum that is distinctive for that element
Must be a gas that is “excited” by high temperature
Emission spectrograph obtains and records line spectra of elements
Needs means for vaporizing elements to emit light
Done by direct electric currents
Component to separate this light
Can be done by a prism
Means to record separation
Substances usually contain more than one element so must match graph to known patterns of elements
Used to identify mutilated bullets, paint chips and glass pieces
Atomic absorption spectrophotometry
Based on principle that elements will absorb same frequencies as it emits when vaporized
Specimen is heated to cause it to vaporize
Specimen is then exposed to radiation source
Best if radiation source is made of a discharge tube

of same element one is trying to identify