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Forensic Science

Forensic Science

Determine whether a crime has been committed
Whether it was committed in "your" jurisdiction
Discover and document all facts pertaining to the complain
Identify and eliminate suspects as a result of collected physical evidence
Locate and apprehend the perpetrator (warrants)
Maintain chain of custody to ensure evidence is admissible in court
Effectively testify as a witness to the collected evidence.

Bertillion

Father of criminal detection
Devised the first scientific system of personal identification, using body measurement, known as anthropometry in 1879
(created the 11 measurement of facial structures to identity peoples faces, markings (moles/ birthmarks, something unique to the individual))

Galton

fingerprints

Lattes

Devised a simple procedure for determining the blood type (A, AB, O) from dried bloodstains. He found out how to rehydrate blood for professionals to examine.

Edmond Locard

Exchange Principle: every touch leaves a trace

Sir Arthur Conan Doyle

Not a forensic scientist
Popularized scientific crime - detection methods through his fictional character sherlock holmes
Through his book, he pushed uncommon crime detection ways

Edward Henry

developed the first classification system for fingerprint identification

Death Investigation

scene investigation, examination of the deceased, identification of the deceased, cause of death determination, production of a death certificate

Deaths must be investigated if any of the following may be true:

- From criminal violence (homicide)
- By accident or by suicide
- Of sudden nature, apparently in good health (you're young)
- When unattended by a physician
- In custody of the state/city (incarcerated)
- In any suspicious or unusual manner

Coroner's System

someone who is a public official (elected or appointed, no formal medical training necessary) to inquiry deaths and complete death certificates.
Started in England AD 925
First in US: Maryland in 1637

physicians with specialized training in forensic pathology

First Medical Examiners of The US

in 1890 in Baltimore Maryland appointed 2 doctors

Forensic Pathologists

a pathologists who studies disease and trauma that lead to death

Pathologists

doctor who studies and diagnoses diseases in humans

Autopsy

standard dissection of body to determine cause of death

Two Types of Autopsies

hospital autopsy
medicolegal autopsy

Five Manners of Death (MODs)

Homicide
Suicide
Natural
Undetermined
Accidental

What does an autopsy entail?

Y shaped incision to see all of the abdominal muscles, skin, and organs
Remove organs
Weighing organs
All Organs Observed
Collect samples that are preserved
Collect samples of microscopic examinations

Questions an autopsy answers about the scene

Who is the victim, what are the injuries, when did the injuries occur, why and how were the injuries produced, (trauma)

Mechanical Trauma Definition and Categories

def: when the applied force exceeds the strength of the tissue (skin, muscle, bone, etc)
categories: sharp force, blunt force, ballistic

Thermal Trauma

applied force from heat that causes damage to tissue or skin

antemortem

sustained prior to death; have healed or begun to heal

Perimortem

occurred at or near the time of death

postmortem

occur after death, considered "modifications" from events such as carnivore gnawing, freeze/thaw, weathering

Ten questions codified by Snow (1982)

1. Is it human?
2. What is the MNI?
3. When did the death occur?
4. What is the age?
5. What is the sex?
6. What is the ancestry?
7. What is the height? (stature)
8. Are there any anatomical anomalies, pathologies, etc?
9. Evidence for cause of death?
10. Evidence for manner of death?

Forensic Anthropology

the application of anthropological techniques to modern human remains for law enforcement

How to answer "Is it bone?"

property tests, experience, weight, appearance, situation/location

How to answer "is it human?"

Locomotion anatomy (We are the only bipeds)
Limb Proportions
Joint Surfaces

Role of forensic anthropologists

identifying human vs nonhuman skeletal remains, how many individuals (MNI)

MNI

minimum number of individuals represented in an assemblage or at a scene

Biological Profile (only for adults)

sex, age, population affinity, stature, individual characteristics

Three bones to estimate sexual dimorphism

- Pelvis (one sex can pass a baby and one cannot)
- Long Bones (size)
- Skull (parts of the skull can be more developed/pronounced which will differentiate men and women) women have more pronounced qualities that are due to development and growth

Subadult Age estimation-biological profile

status of growth and development, bone formation and growth, teeth: development and eruption, dental sequences, and epiphyseal fusion

Adult age estimation-biological profile

degenerative changes in skeleton

fetal/neonate age estimation

long bone length

stature-biological profile

metric assessments: Measurement system to make statements about biological profile

Biomechanics

- bone will bend, deform, and then fail
- Stronger in compression, fails in tension first
- For ballistic impacts, merely fails; sharp force too (does not have deformation)

Recognize there is some deformation when it comes to blunt force trauma (the bone is not going to be the same way it was before

Characteristics of sharp force trauma

Sharp and straight margins (nothing in the body is straight or sharp)
Blade striae
Shearing off of bone surfaces

What can you conclude from sharp force trauma?

"Cut Marks"
Saw Marks - linear striations from a saw and its going through a large surface
Mechanical or hand

Decomposition:

system breakdown of tissue

decomposition is influenced by

extrinsic processes (environment, animal/insects), intrinsic processes (cell death, gut bacteria)

Stages of Decomposition

1. Fresh
2. Bloat
3. Active decay (early)
4. Advanced decay (advanced)
5. Dry Remains (skeletonization)

Ballistic Wounds

smaller entry wound
bigger exit wound

Beveling

cone shaped bone erosion in the direction of a bullet path through the skull

DNA submitted to labs follow this process:

Extraction: release DNA from the cell
Quantitation: determine how much DNA you have
Amplification: produce multiple copies of DNA in order to characterize it.
Separation: separate amplified DNA to permit subsequent identification.
Analysis and Interpretation: quantitatively and qualitatively compare DNA evidence samples to known DNA profiles
Quality Assurance: review analyst reports for technical accuracy

Partial Electropherogram - STR (short tandem repeat)

The number of peaks shows how similar the alleles are.
One or two peaks at each locus: one if they inherit the same allele from each parent.
The numbers come from dna profiling
Observing and tallying at each of the loci: the amount of repeats

DNA Profile

A distinctive pattern of DNA fragments that can be used to match a biological sample to an individual

Mitochondrial DNA (mtDNA)

- mtDNA fragments are likely to remain long after similar sized fragments of nuclear DNA have been lost.
- Due to both the structure of the mtDNA molecule and sheer number of mtDNA molecules present in a cell.
- mtDNA is maternally inherited; any maternal relative can provide reference sample.
- (if found DNA at crime scene is male, don't go find his children because he won't share the same mitochondrial dna)

Radiating Fracture

what comes out from impact site of blunt force ; impact is absorbed and there are pushed out from the central points

Concentric Fracture

fractures forming in an approximately circular pattern around the point of impact

ACE-V

Purpose is to identify an item via individualization as having originated from the same source or exclude items from having a common origin
- Analysis: do u have a question and knowledge and are they worthy of study?
- Comparison: compare the questioned item
- Evaluation
- Verification: examiners conclusion studied by second examiner (i.e. technically peer review)

Mathieu Orfila

established forensic toxicology as a legit science (father of forensic toxicology)- blood and tissue

Albert S Osborn:

- Developed fundamental principles of document examination
- Responsible for acceptance of documents as scientific evidence by the courts

Calvin Goddard:

used a comparison microscope to determine if a particular gun fired a bullet

Walter C McCrone:

father of microscopy (using microscope to see things that the naked eye cannot)

J. Edgar Hoover

- director of the FBI during the 1930's
- Organized a national laboratory to offer forensic services to all LEA in US

Classifying Evidence

Questioned Evidence - original source is unknown. What you collected as evidence.

Known Evidence - we know where the source originated. Via a warrant collected from suspect

Methodical Approach to Scene Processing:

General crime scene guidelines: Initial scene assessment
- Search for and recognition of physical evidence
- Documentation
- Collect it
- Package and preserve it
- Crime Scene Recognition

Provenience

where an object is recovered in situation

Provenance

life history of an object

Toxicology and Poisons

Poison is small dose is medicine
Medicine in a large dose is poison

Toxicologists must determine:

IDENTIFY of all drugs and poisons in the body
QUALITIES of all drugs and poison in the body
METABOLITES of all drugs and poisons in the body
INTERACTIONS of all drugs and poisons in the body

Pharmacokinetics

Science concerned with how drugs move into and out of the body

Four Processes of Pharmacokinetics

1. Absorbed into the bloodstream
2. Circulates; distributed throughout the body
3. Metabolized for intended/unintended effects
4. Eliminated from body

How to identify drugs in the body

1. Sampling - Bloods and urine (hair perhaps)
2. Extraction - tissue or fluid removed and then drug extracted from it
3. Screening
4. Confirmation

Blood Evidence

Blood Droplets - analysis: clues to location of crime, moment of victim/suspect, etc..

Blood Spatter - analysis determines patterns that give investigators clues re. Crime, ie. directionally, type of weapon, etc.

Blood Samples: analyzed to determine blood type and DNA, can be matched to possible suspect of victim; collect knowns.

Important Dates:

1923 - Frye vs United States
1986 - Sanger Sequencing (DNA) commercialized
1993 - Daubert vs Merrell Dow Pharmaceuticals
2004 - NCIS first season
2005 - Next Generation Sequencing (DNA), originally invented in mid 1990's, becomes widely available for commercial use
2009 - "Strengthening Forensic Science in the United States : A Path Forward" AKA the NAS REPORT

Categories for Bloodstain

1. Passive bloodstains
2. Contact/Transfer bloodstains
3. Projected (impact) bloodstains
4. Miscellaneous (void: shadow is blood stain is big enough and someone else's shadow)

Things that can change the timing of decomposition

- Temperature
- Humidity
- Buried (no oxygen) or submerged in water (no oxygen)
- Exposure (wrapped in clothes, wrapped in plastic)
- Sun vs shade
- Tiny vs Very Large

Forensic pathology finds out...

Who is the victim?
What are the injuries?
When did the injuries occur?
Why and how were the injuries produced?