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

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 ExaminerIt 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

authorizationThe 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

mis-identified 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

findingsThe 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.

REAL LIFE FORENSIC SCIENCE

Fact Vs. Fiction

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 CaeserIn 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)

Fingerprints Aren’t Foolproof

• NO TWO PEOPLE CAN HAVE IDENTICAL FINGERPRINTS

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

• 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

DNA testing has cleared more than 242 convicted criminals of false charges

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

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 NamlahThird year Medical Students, King Saud University

Faculty Members

• Prof. Abdelmoty Mohamad Kamal Kabbash– Professor and head of Forensic Medicine &

Toxicology UnitCollege 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