ETX 20 Final

Murder of Penny Parker

- Penny parker disappeared while collecting money for her paper route

- Found dead three days later and secually assaulted

- not enough tehcnology or evidence to charge

- semen was on underwear so it was entered in national database but no match

- samoles from ex wife and biological duaghter of don jennings was taken

- detectives took sample from mr jennings and it matched the dna

Forensic science is science used ...

In public, in a court or in the justice system

In its broadest def., forensic science is...

The application of science to criminal and civil laws

Forensic Science

Application of science to evidential items ( physical evidence ) handled in a crime lab

Criminalistics

Scientific analysis of evidence from crime scenes, including interpretation of evidence to reconstruct crime scenes

criminal court

- pay debt to society and protect rest of society

- indictment/arrest or citation

- charges: felony, misdemeanor, infraction

- standard of proof: beyond a reasonable doubt

Civil court

- torts: plaintiff (victim) to obtain compensation from defendant

- assign fault for event

- actual damages

- punitive damages

- standard of proof: a preponderance of evidence

Adversarial system: Prosecutor or plaintiffs attorney

Convince jury/judge of defendants guilt

- motivation, opportunity, evidence of involvement

Adversarial system: Defendants attorney

Convince jury/judge of defendants innocence

- discredit evidence, provide alibi

Expert witness aspects

- interpret the evidence

- not part of prosecution or defense team

- special knowledge and skill, training, education

- remain in expertise

- open to challenge by opposing counsel

The increase of crime labs is due to:

1. Supreme Court decision in the 1960s responsible for police placing greater emphasis on scientific evaluated evidence

2. Crime labs inundated (overwhelmed) with drug specimens due to accelerated drug abuse

3. Advent of DNA profiling

What does a crime lab do?

1. Toxicology

2. DNA analysis

3. Firearms

4. Trace evidence

Who does the work and what do they do specifically?

1. Detectives - interview suspects, make arrests

2. Crime scene technicians - respond to crime scene, collect evidence, reconstruct what happened

3. Forensic laboratory scientists - analyze physical evidence, conduct methods, development research

Forensic Science

Application of science to evidential items ( physical evidence ) handled in a crime lab

Criminalist

The one who analyses, characterizes and identifies physical evidence, forms an opinion and testifies to their opinion in a court of law

Criminalistics

Scientific analysis of evidence from crime scenes, including interpretation of evidence to reconstruct crime scenes

Criminalistics (crime) laboratory:

This refers to a lab that has the capability to perform all the tests normally associated with the field of criminalistics or forensic science ( have sophisticated strummers and staff have degrees )

What are a criminalists duties?

- analyze physical evidence

- conduct research or studies

- prepare a written report

- testify to their results in court

- respond to crime scenes

- collect evidence

- reconstruct what happened at a crime scene

Duties: analysis of drugs and clandestine labs

- analysis of drugs

- use sophisticated instruments to obtain results such as Gas Chromatography Mass Spectrometry GCMS

- testify to your analytical results in court

Duties: Analysis of Alcohol & Drugs (Toxicology)

- analysis of blood, breathe, or urine for alcohol

- testify in court to analytical results

- be able to explain to the jury why all people are impaired and unsafe drivers at 0.08% alcohol

- analysis of blood, urine and tissue for drugs and narcotics

Duties: DNA Analysis

- analysis of blood, bone, hair, saliva, seminal fluid for dna using the STR technology (Short Tandem Repeats)

- use DNA equipment such a thermocycler to amplify dna, and the capillary electrophoresis analyze the dna pattern

- testify in court, develop and defend complex dna statistics

Duties: Trace Analysis

- analysis of paints, hairs, fibers, soils, ropes, tapes, explosives, arsons

- use sophisticated instrumentation

- testify to your results in court

Duties: Firearms Analysis

- determine if a bullet or cartridge case was fired by a weapon

- reconstruct shooting incidents using trajectory techniques

- determine gunshot residue on shooters

Trace Evidence

- most complex field

- very labor intensive and expensive

- without dna, the only resource for homicide cases

What is the goal for criminalists?

The science of individualization

Ex) Can this bullet be traced to gun barrel?

Does this DNA match the victims DNA?

The KEY to forensic science is...

the forensic association and the significance of the association

Locate exchange principle

Every contact leaves a trace

Forensic Associations

1. Crime scene

2. Evidence

3. Suspect

4. Victim

The Capacity to make forensic associations depend of the validity of four premises :

1. That many kinds of biological and physical entities exist in unique form or become unique

2. These entities leave corresponding unique traces of themselves

3. The techniques of observation, measurement, and the inference by forensic science are adequate to associate these traces back to the object that produced them

4. These associations are scientifically significant

Computer analysis

- comparison

- transaction

- deleted files

- keyword searches

- passwords

Explosive analysis

- identify residue

- determine manner in which the device functioned

- construction characteristics

- device components

Fingerprints

- dna

- trace drug residue

- explosive residue

Feather analysis

- determine species

- compare to other feathers

Footwear and tire tread analysis

- connect to suspect

Glass analysis

- fracture patterns

- broken glass

- cell phones

- film on glass

Human hair analysis

- forcibly removed

- artificial treated

- damage- crushed

- burnt

Ink analysis

- Ink varies with type of writing instrument, ballpoint pen, fountain pen, porous-tip pen

- Ink varies with the date of manufacturing

Paint analysis

- the questioned paint layer structure can be compared to a known paint source

- the sequence, relative thickness, color, texture, number, and chemical composition of each layer can be compared

Polymer analysis

- make, model, and model year of car can be determined if manufactures part number is on the trim

- plastics in wire insulation and miscellaneous plastics such as buttons can be compared with known sources

Questioned documents analysis

- paper

- examined for indented writing

- burned or charred paper may be deciphered

- anonymous letter file

- plastic bags

Ropes and Cordage Analysis

- a piece of rope or cord can be compared with a questioner rope or cord

- composition, construction, color, and diameter can be determined

- knots

Soil analysis

- determine if soils share common origin by comparing color and texture

- collect soil samples as soon as possible

Tape analysis

- composition, color, and construction can be compared with known sources

- end matches

Textile fibers analysis

- natural fibers and synthetic fibers

- easily transferred

- evidence of contact

- evidence of recent contact

- carpet fibers

Toolmark analysis

- tools can bear unique characteristics

- fracture - can be determined whether evidence was joined together or apart

Toxicology analysis

- because of the toxic substances it may be necessary to screen for class of poisons

- volatile compounds

- heavy metals

Repeat: Forensic Diamond/ Associations

1. Crime scene

2. Evidence

3. Suspect

4. Victim

Cause of death

The specific injury, trauma, or disease that was responsible for the lethal sequence

Manner of death

explains how the cause of death arose

Manner of death categories

1. Natural

2. Accident

3. Suicide

4. Homicide

5. Undetermined

Forensic pathologists

- must reach an unbiased conclusion

Natural Causes of death definition and rankings

1. Heart disease

2. Cancer

3. Chronic lower respiratory disease

4. Stroke

5. Accidents

Accidental causes of death in ranking

1. Motor vehicle

2. Poisoning

3. Falls

4. Fires

5. Choking

Suicides causes of death

- 11 attempts for every one successful event

- 38,000 suicides per year

Who is most likely to commit suicide and who is most likely to have suicidal thoughts?

- suicides among males is 4 times greater than females

- females are more likely than males to have suicidal thoughts

What method is commonly used to commit suicide among males?

Firearms ( 56% )

What method is commonly used to commit suicide among females?

Poisoning ( 37.4% )

Postmortem Changes: Necessary Interdependent Systems for Life Order of Shutdown

1. Respiratory system

2. Circulatory system

3. Central nervous system

4. Cellular metabolic pathways convert to autolytic activity which leads to cell death

DECOMPOSITION STARTS ON THE INSIDE OF THE BODY

Early Postmortem Changes

- cessation of respiration and blood circulation

- skin pallor ( paleness )

- muscle relaxation

- eye changes

- blood coagulation

- loss of bladder muscle tone

- semen may be emitted

- gastric contents are commonly "regurgitated"

- defecation

Postmortem Changes and Time of Death Indicators

THERE IS NO SINGLE ACCURATE MARKER TO DETERMINE TIME OF DEATH

- unless actually being there during the death

Classic (not accurate) Markers of Death

- Degree of Rigor Mortis (stiffening of the muscles)

- Amount and position of Livor Mortis ( coagulation of blood )

- Algor Mortis (deceased body temperature)

- presence and extent of insect infestation

- skin pallor

- changes in the eyes

Rigor Mortis

Muscular relaxation —> Rididity —> Muscular relaxation

- muscle cells may continue to metabolize glycogen to lactic acid causing a lock in the body

Unreliable marker for estimating time of death

Rigor mortis (temp. dependent)

- heat accelerates the chemical process

- cold decelerates the rigor process

- lower ph accelerates the process

Rigor Mortis (Mechanism —> ...)

Mechanism: Physical change

Onset: Immediate

Manifested: 1-6 Hrs

Maximum: 6-24 hrs

Disappears: 12-36 hrs

Unreliable marker for estimating time of death

Livor Mortis

(Discoloration) blood settling to the lowest point in the body

No hydrostatic pressure of liquid blood causes the blood to settle in the lowest capillary beds

- red/purple= usual

- pink= cyanide or cold temp

- cherry red= carbon monoxide

- brown= nitrates

- color varies according to skin pigmentation

Can indicate if a body has been moved after death

Livor Mortis (Mechanism —> ...)

Mechanism: settling

Onset: immediate

Manifested: 2-4 hrs

Maximum: 8-12 hrs

Algor Mortis

The cooling of the body after death

- body temp is not fixed

- 98.4 - rectal temp divided by 1.5 = hrs since death

- activity, illness, decomposition, infection, absorption of heat can maintain or raise body temp after death

Unreliable marker for estimating the time of death

Evidence for estimating time of death:

1. In the body

- beard, nails, hair

- stage of decomposition of organs vs exterior

2. Environment

- uncollected mail

- lights

- clothing

- alarm

3. Decedents ordinary habits and daily activity

- work and school schedules

- appointments

4. Food in the stomach

Food in the stomach time and size

Light = 1.5 - 2 hrs

Medium= 3 - 4 hrs

Heavy= 4 - 6 hrs

Liquids = minutes

Solids = several hours

Vitreous Potassium

Determination of vitreous (eye fluid) potassium concentration

- calculations are most accurate when done 12 hrs within death

Equation used to determine the time of death based on a potassium leak rate of 0.14 milli-equivalents/liter/hour:

(7.14 X K+ concentration) - 39.1 = hours since death

Formula for Vitreous Potassium

(7.14xK + concentration) - 39.1 = hrs since death

Decomposition involves two major components:

1. Autolysis

2. Putrefaction

Autolysis

process by which digestive enzymes within the body cells break down carbohydrates and proteins (usually starts in the pancreas)

Putrefaction

The major component of decomposition which is the breakdown of proteins due to bacterial and fungal activity

Death and Violent Crime Scenes

1. Document and evaluate body

2. Preserve evidence on the body

3. Examination of the clothing

4. Complete physical description

5. Collect personal effects

Court System: Trier-or-fact

- Who is this?

- What do they determine?

- How do they determine?

Truth in witness statements established through the presentation of information/evidence

Different Types of Evidence/Information

- personal testimony

- language on documents

- material objects

Evidence is given in a legal investigation to make a fact or proposition more or less likely

Key Examples of Type of Evidence

1. Real evidence - generated as part of a crime and recovered from crime scene

2. Demonstrated evidence - created later to augment/explain real evidence

Basis of Evidence

1. Transfer

2. Persistence

Transfer

- Locard Exchange Principle: when two things come in contact, info is exchanged

- result of transfer= proxy data, remnants/history of that transfer

Conditions that affect Transfer:

1. Pressure applied during contact

2. The number of contacts

3. How easily the item transfers material

4. The form of the evidence

5. How much of the item is involved in the crime scenes

= direct (w/no intermediates) or Indirect

Persistence

After it transfers, evidence will remain and persist until it...

- further transfers

- degrades to unusable/unrecognizable

- collected as evidence

Identity

Examination of chemical and physical properties of an object

Identify allow GROUP categorization

Class

Used to further sub-categorize within a group

Class identity may indicate common source

Individualization

An object classified into a group w/only one member (itself)

UNIQUE; allow for individualization

Ex of Identity, Class, and Individualization

- Identity: Group, —> Hair

- Class: Sub-group, —> Human Head Hair

- Individualization: —> Matt woods head of hair

Known Evidence and example

Evidence from a defined source

Ex) paint chips collected from a car

Questioned evidence and example

Evidence where the original source is unknown

Ex) paint chips collected from a hit and run victims jacket

2 Fundamental Processes of Analysis of Evidence

1. Identification: discover physical/chemical characteristics + classify/individualize

2. Comparison: establish the source of the evidence

Evidence: Comparison and Example

Controls

- materials from known source

- used to compare with unknown evidence

Ex) Red stains on shirt

Evidence Controls: Red stain on shirt - Negative

Stain isn't blood

Stain is blood, test was bad

Shirt interfered with the test

Evidence Controls: Red stain on shirt - False Positive

Type 1 error

(Test says stain is blood but is not)

Evidence Controls: Red stain on shirt - False Negative

Type 2 error

(Test says stain is not blood but is)

Analysis of Evidence: Scientific Method Process

Proposing and refining plausible explanations about an unknown situation

- testability —> are the questions testable?

- repeatability —> is the science repeatable?

BPA stands for

Bloodstain Pattern Analysis

Goals of BPA

Determine the what, when, and where of bloodstain events

What- answered by size of stains and appearance

When- conditions of stains (wet v dry)

Where- area of convergence and location of source

Why conduct BPA?

- direction of impact

- mechanisms by which spatter patterns

- understand how the bloodstains were deposited onto items of evidence

- determine position of victim

- corroborate witness statements

- prove or disprove statements

- identify number of offenders

- establish sequence of events

BPA

Analysis and interpretation of the dispersion, shape, characteristics, volume, pattern, number, and relationship of bloodstains at a crime scene to reconstruct a process of effects

- combination of geometry, physiology, physics, and logic

What is blood?

Liquid

- plasma and serum (plasma-clotting factors= serum)

Solids

- red blood cells, white blood cells, glucose, nutrients

3 Main Classes of Bloodstains

1. Passive/ Gravity

2. Spattered

3. Altered