Transcript Real Life Forensic Science

Forensic Science
An Introduction
What Is Forensics?
• Forensic science is the application of
science to law
• Forensic scientists: are primarily
concerned with examining contact trace
material associated with crimes. This
follows the principle that 'every contact
leaves a trace' that will offer potential
evidence to link a suspect with the scene of
the crime, the victim or the weapon.
Typical Work Activities: The
Forensic Lab
• Chemistry - the examination of paint, chemicals,
etc., including fire investigation and accident
reconstruction;
• Biology - DNA testing and the examination of
minute contact traces, such as blood, hair, clothing
fibres, etc.;
• Drugs and toxicology - testing for restricted
drugs, examining tissue specimens for poison
detection, and the analysis of blood and urine
samples for alcohol, for example in drink driving
offences.
Forensic Sciences: The Big Umbrella
• Forensic Chemists: the forensic chemist studies
the molecular aspects of the crime scene.
• Forensic Anthropologists - The forensic
anthropologist examines the victims bones to
determine a number of key facts.
• Forensic Dentists/Odontologists - these experts
serve an identification function by analyzing a
corpse's teeth and previous dental records.
• Forensic Linguists: the forensic linguist analyses
either the spoken or written word..
Forensic Sciences: The Big Umbrella
• Forensic Artist: the forensic artist provides an
elaborate sketch of the offender.
• Forensic Sculptors: like the forensic artist, the
sculptor attempts to create an image of either an
offender or a victim. The sculptor's goal is to
create a three dimensional version of the image.
• Ballistics Experts: ballistic experts focus on the
functioning of firearms
• Dactyloscopy: this is the scientific analysis of
fingerprints.
Forensic Sciences: The Big Umbrella
• Forensic Entomologists: study insects and key
information can be discovered such as the rate of
body decay via insects can directly correlate to
time of death.
• Forensic Geologists: the forensic geologist can
determine where a person or object has been by
analyzing soil samples.
• Forensic Serologist: the serologist studies blood
and other bodily fluids for identification
purposes.
Forensic Sciences: The Big Umbrella
• Forensic Pathologist: the forensic pathologist
analyzes the remains of a body. They attempt to
determine the cause and time of death via
autopsy.
• Forensic pathologists are trained to conduct
comprehensive death investigations.
• They require a medical degree, followed by
several years advanced training in pathology.
Forensic Pathology: Investigation
History
Laboratory
Studies
Forensic
Investigation
Imaging
Studies
Physical
Examination
The Medical Examiner
• A medical examiner is a medically
qualified government officer whose duty is
to investigate deaths and injuries that
occur under unusual or suspicious
circumstances, to perform post-mortem
examinations & in some jurisdictions to
initiate inquests
The Medical Examiner
It is not the authority, nor the responsibility of the
Medical Examiner's Office to investigate or be
involved with any 'medicolegal' issues
In cases of death that fall under the jurisdiction of the
Medical Examiner, the body of the deceased must not
be moved without Medical Examiner authorization
The differentiation between natural deaths and
unnatural deaths is the appropriate focus of the
Medical Examiner's Office.
The Medical Examiner's conclusions are intended to be
shared with the public.
The Crime Scene Investigation
• The real crime scene investigators are highly trained
police officers (Identification Officers)
• They are trained in all aspects of crime scene
analysis from photography, fingerprinting and DNA
collection to blood spatter pattern analysis
• The identification team collect the evidence, and
submit it to the forensic scientists at the lab, who
will then perform the analyses and submit reports to
the Investigating Officers
The Crime Scene Investigation
The identification officer handles the crime scenes and is
not responsible for other aspects of the investigation
Other police officers are involved in such things as
interviewing suspects and following up leads
NO mistakes are allowed
Therefore, every Identification specialist can
state in court, that they have NEVER misidentified anyone
The Autopsy
• The Definition of “Autopsy”: ‘to see for one's
self.’
• It is not the same as the word “dissection”:
‘the process of disassembling and observing something
to determine its internal structure and as an aid to
discerning the functions and relationships of its
components’
• It involves:
observing the external and internal structures of the
body to gain information about the individual's
death
The Autopsy
• 'What do you look for at autopsy?’
Anything and everything
– Is there evidence of abnormal development?
– Is there evidence of natural disease? Is there
evidence of injury (physical, electrical, heat, cold,
drug, chemical, radiation)?
– Are there clues to the identity of the deceased?
– Is physical evidence related to an unnatural event
present?
The Autopsy
The goals of the forensic autopsy are:
• to discover information that cannot be obtained in other
ways
• to provide independent confirmation of what is known or
• to provide a variety of means of documentation of findings
The performance of an autopsy is an important forensic tool
to be applied to certain cases as needed, NOT AN END POINT,
and not a 'lab procedure' done on request.
The Medical Examiner has statutory authority to perform
autopsies and post mortems.
Fact Vs. Fiction
REAL LIFE FORENSIC
SCIENCE
Who Invented Forensic
Science?
NO, NOT SCIENTISTS
“Necessity is the mother
of invention”
The use of fingerprints by
the police to identify
criminals was the first
real application of
science to LAW
Forensics: An Ancient Science?
• The first crime claimed to have been
solved by forensic science was:
The murder of Julius Caeser
In 44 B.C.
Fingerprinting
• Who were the first to use fingerprints in a legal
system?
The Chinese used fingerprints to establish identity of documents &
sculptures
• When was the first fingerprint filing system devised?
In 1899, by Sir Edward Richard Henry, in his book “Classification and
Uses of Finger Prints” – the system is still used by the FBI today
• What system of identification was used before
fingerprints?
Bertillonage system; measuring people’s bodies. The system used 11
measurements
• What is the main system used by law enforcement
for matching fingerprints today?
The Automated Fingerprint Identification System (AFIS)
• NO TWO PEOPLE CAN HAVE IDENTICAL
FINGERPRINTS
Fingerprints Aren’t Foolproof
Their patterns are so intricate and variable that it
takes a well-trained eye to recognize a match.
Computer technology has made this process a lot
easier, but there is no completely foolproof method.
• EVEN GLOVES LEAVE PRINTS
• UV RAYS CAN REVEAL INVISIBLE PRINTS
• GETTING A FINGERPRINT OFF HUMAN SKIN IS
NEAR IMPOSSIBLE
Loops are the most common type
Matching fingerprints is not an easy job
DNA Testing: The Star of the
Show
DNA testing has cleared more than 242 convicted
criminals of false charges
• Deoxyribonucleic acid is a nucleic acid containing the genetic
instructions used in the development and functioning of all
known living organisms
• It occurs as linear chromosomes; a set of chromosomes makes
up the genome – and is divided into discrete units called
genes
• Genes are translated into proteins
• It is present in ALL the cells (in the nucleus and
mitochondria)
• A minute amount is all that’s needed for analysis
Unique DNA?
• How much of your DNA sequence do you
share?
– With mice: 92%
– With chimpanzees: 98%
– With humans: 99.9% (~100%)
You have 2 copies of every gene sequence, 1
from your mother, and one from your father.
They are usually not identical. They code for
“traits”; this determines your appearance &
whether you carry any diseases.
DNA Analysis
• Only about 1.5% of the human genome consists of
protein-coding sequences, with >50% of human DNA
consisting of non-coding repetitive sequences called
'short tandem repeats' (STR's)
• The number of times the STRs repeat varies between
individuals
• This allows for
identification.
http://www.sciencephoto.com/media/211366/enlarge
Unidentifiable Victims
• Often murder victims are discovered at
advanced stages of decay.
• This makes immediate identification of the
body almost impossible.
• Investigators have resorted to precise
scientific methods to determine the
identity of the skeletal remains.
Facial Reconstruction
• Once the skin and flesh has rotted away
from the skull of a corpse, their character
and physical appearance disappear along
with it.
• Clay is used by sculptors and
anthropologists to reconstruct a life like
form of what the person looked like from
the skeleton.
Thus helping identify the victim.
How Is This done?
• Depth of the skin must be measured.
– Facial depth measurements are available for
male and female, certain ages, racial groups,
thin people and obese people
• Concentrate on facial features
– The eyes, mouth, ears, nose, chin, jaw and
cheeks.
– These give the face the most character.
• The Face:
– Sculptors must build the
muscles around the
skull.
– They are able to
approximate the size
and insertions of the
facial muscles by noting
the shape and size of the
bones of the face.
– The sculptors then cover
the clay muscles with a
layer of clay skin which
is smoothed over to
resemble real skin.
Teeth Are Trustworthy
• Dental records are responsible for identifying up to
93% of corpses.
• Most reliable form of identification:
– Every individual has a unique dental imprint
– Sturdiness of bones means they are the best
preserved human remains.
• Identification for unrecognizable victims.
E.g.: Burning, Mutilation, Disfigurement of the
body
Bullets Aren’t Foolproof
• Bullets are similar to fingerprints in the
sense that the barrel of each gun has its
own unique grooves and surfaces.
• This creates a distinct imprint that acts as
the “fingerprint” of the gun.
• However, a bullet can be damaged upon
impact, so finding a matching pattern
becomes more difficult.
Although authorities have been able to trace
weapons from the bullets they fired (and from
those who fired the weapons), the process itself
is extremely meticulous and open for error.
What can bones tell us?
• Age:
–
–
–
–
Teeth
Collar bone
Vertebral bodies (spine)
‘Ossification’
• Gender
– Skull & hip bones
• Height
– Reassembling the whole skeleton &
measuring the length of the significant
bones
• Race
– Skull
Piecing It All Together
The
Autopsy
Crime
Tools
The
Suspects
The
Crime
Scene
The
Evidence
Identity
Thank You
Questions?
Thank You
Students:
• Jude Al Masoud
• Sara Al Munif
• Norah Al Saif
• Roa Al Sajjan
• Moneerah Al Gassim
• Sarah Mahasin
• Zeinah Al Halees
• Lara Al Namlah
Third year Medical Students, King Saud University
Faculty Members
• Prof. Abdelmoty Mohamad Kamal Kabbash
– Professor and head of Forensic Medicine & Toxicology
Unit
College of Medicine - King Saud University
• Dr. Khaldoon Aljerian
– MBBS, MHSc, FRCPC
– Forensic Medicine Unit, Department of Community
Medicine, College of Medicine - King Saud University
• Dr. Theeb Alqahtani
– Forensic Medicine Unit, Department of Community
Medicine, College of Medicine - King Saud University