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Introduction to Forensic Science

Unit 1: Introduction to
Forensic Science
Definition and Description of Forensic Science
Forensic Science (informal) is the application of science to law
Forensic science (formal) is the application of science to those criminal and civil laws
that are enforced by police agencies in a criminal justice system
A forensic scientist specializes in one specific area and my have from 4 – 12 years of
post-secondary education in addition to continuous and on-going training
The CSI effect is where the court system has false expectations of what can and cannot
be expected from the crime lab
Generally, there are two fields:
o Crime lab scientists are bench scientists, that is, they spend their day in a
laboratory, analyzing specimens
 They do not attend crime scenes (with rare exceptions)
 Have strong core scientific backgrounds who perform scientific analyses
on evidence
 They attend court to testify as expert witnesses
o Crime scene investigators (also called identification specialists) are specially
trained police officers in the RCMP or major crime officers in municipal and
provincial police forces
 They collect evidence at the crime scene
Crime labs usually include the following units:
1. Case receipt unit
 Evidence collected at crime scene is taken to the crime lab then enters
 Every single exhibit is tagged with a computer code
 Allows its movements through the various units of the lab to be
monitored at all times
 Many analyses require a small portion of the exhibit to be destroyed and
this will be recorded
2. Evidence recovery unit
Once tagged, the exhibit will go to the ERU, where scientists will then
examine the exhibit looking forensically for trace evidence
 ERU technologists will search, locate and collect all forensically important
material and submit it to the appropriate unit
3. Forensic biology unit
 Deal with body fluids
 E.g. Blood, semen, tissue or hair
 The purpose of their analyses is to identify the person the substances
came from
 Used to be called the serology section, but changed after discovery of
DNA analysis
4. Forensic toxicology unit
 Quantify toxins (primarily drugs and alcohol, but also poisons) in body
fluids and also in needles, pills etc.
 They also determine the physiological effects of such toxins on the
5. Trace Evidence Unit
 Used to be called forensic chemistry
 Analyze any non-biological substance found at a scene
 E.g. Paint, fibre, glue gasoline etc.
 They are the main scientists involved in hit and run, break and enter,
arson, and terrorist crimes
6. Firearms and Tool Marks Unit
 Compare tool marks and firearms in order to determine whether a tool
made a certain mark
7. Questions Documents Unit
 Look primarily at handwriting to determine whether a person wrote a
suspect document
 They look at documents to see whether they have been altered
 They look at machines like fax machines and printers that produce
Scientists vs. Technicians
o Technicians assist scientists and run part or all of the chemical analyses
o Scientists oversee the work, perform the interpretations, and write the reports
and they may eventually testify in court
o 1910: Edmond Locard created the first forensic laboratory in the world in Lyon,
o 1914: The first forensic laboratory in North America was established in Montreal,
o 1923: The first forensic laboratory in the US was established in Los Angeles,
o 1931: FBA laboratory was established
Canadian Crime Laboratories
o Three RCMP labs in Vancouver, Edmonton and Ottawa (as of 2014)
 Deal only with criminal cases for all official investigative agencies
 Vancouver does firearms and toxicology analyses
 Ottawa does toxicology, firearms, questioned documents and
trace evidence
 Edmonton does toxicology and trace evidence
o The Centre of Forensic Sciences in Toronto and Sault Ste. Marie, Ontario
 Deal with cases for investigative agencies and also for defense counsel
 May also deal with civil cases
 Consists of the following sections:
 Biology
 Electronics
 Chemistry
 Firearms and
 Documents
and photo Toxicology
o Laboratoire de sciences judicaires et de medicine legale in Montreal
 Available to any organization in Quebec requiring their services such as
police agencies, corrections, the coroner’s office, the Department of
Natural Resources and Wildlife, the Commission of Health and Safety at
Work and Departments of liquor, gaming and racing
 Consists of the following sections:
 Biology
 Questioned
 Toxicology
 Gaming
 Chemistry
 Toolmarks and
 Explosives
 Photography
The forensic strategist assists the investigators and forensic ident specialists with
complex cases, providing specialized knowledge to assess the scene and exhibits
Role of the Expert Witness
Two major types of witnesses:
o Lay or material witnesses who saw or heard something relevant to the case
 Tells the court what he or she saw or heard
 He or she cannot give an opinion
o An Expert witness is someone who didn’t see the event take place but instead
has examined the evidence
 No other kind of witness is allowed to give opinion evidence
 Usually a police officer and a forensic scientist
 Has specialist knowledge in a specific area
Rules of Evidence
Frye v. United States, in 1923, in the District of Columbia
o Required for a forensic science to be recognized—known as the Frye standard
o States that before a science can be admitted into court it must be generally
accepted and well established in the appropriate scientific community
Federal Rules of Evidence (Rule 702)
o Referred more to the reliability of the expert witness themselves and was based
on their qualification, whether the testimony was factually based, based on
reliable methods and principles and whether the witness had reliably applied
these principled
Daubert v. Merrill Dow Pharmaceuticals, Inc.
o Made the trial judge the gatekeeper, and left it to him/her to determine whether
the evidence should be admissible
o Main recommendation was that a scientific technique should be able to report
an error rate
Kumho tire Co. Ltd. V Carmichael (1999)
o Upheld the gatekeeping role of the judge and added that this role applied not
just to the scientific evidence itself but also to all expert testimony
Dulong v. Merrill Lynch Canada Inc. (Canadian)
o Emphasized the role of the judge as the gatekeeper
Main case: R. v. Mohan [1994] 2 S.C.R. 9
o Justice Sopinka stated that expert evidence could only be admitted if:
 It is relevant to the case
 Necessary to assist the trier of fact (judge/jury)
 Did not trigger any exclusionary rules
Presented by a properly qualified expert
Recent Issues in Forensic Science
The NAS Report’s 13 Recommendations
1. A new independent body, the National Institute of Forensic Science (NIFS) should
be funded
2. NIFS should develop standard terminology for reports and testifying
3. Research needs to be conducted in issues of accuracy, reliability and validity
4. Funds provided to make all public forensic laboratories independent of law
enforcement agencies/prosecutors’ offices
5. Research conducted on human observer bias and error
6. NIFS work with National Institute of Standards and Technology to develop tools
7. Forensic labs must be accredited and all forensic scientists must be certified
8. All labs must have routine quality assurance/control measures in place
9. NIFS should establish a national code of ethics
10. Funds provided to educational establishments for grad programs in forensic
science and for scholarships
11. Eliminating all coroner systems and replacing with medical examiner systems
12. Funds provided to develop nationwide fingerprint interoperability
13. Funds provided to NIFS, FBI and Centres for Disease Control to prepare scientists
for events related to homeland security
#7 and #9 may be problematic
o Many scientists are board certified and the boards have codes of ethics and
measures for people to abide by
o However, some sciences do not have boards
o Board certification may exist but only for those with a PhD, whereas in reality,
many scientists hold only an MSc
#4 may be problematic
o Moving labs from police agencies to independent bodies will cause headaches
Introduction to Trace or Physical Evidence
Trace evidence is physical evidence which includes like hair, fibre, body fluids,
fingerprints, gasoline, paint, blood spatter etc.
Locard’s Exchange Principle: when two objects come into contact with one another,
there is an exchange of materials between them
Analyzing evidence involves determining what it is, how common it is, and whether it
can be matched to a known sample
Evidence is analyzed by identification and comparison
o Identification: determining the physical or chemical characters of the substance
being examined
o Comparison: refers to comparing one piece of evidence with another or with
reference material to determine whether they have a common origin
Class and Individual Characteristics
Evidence that has class characteristics can be associated with a group but not a single
o Some class evidence is of little value, but others may be very valuable
o Depends on the significance of the evidence  the probability of the evidence
being found elsewhere
Evidence that have individual characteristics (also called accidental characteristics) can
be identified with just one source with a high degree of accuracy
o Evidence of individual characteristics is extremely valuable and has high
Problems with Class Characteristics
It is of little value if you do not know the probability of another person or car or
whatever having the same class evidence
To determine probability:
o Examiner must determine how many other such items are available
o If data available on the product and several types of class evidence are found
related to the suspect, these can be added to increase significance
o If probabilities could be obtained on each item, they can be multiplied to
determine the probability that anyone else might have evidence on them
History of Death Investigation
All deaths are investigated even if it seems that the death is obviously a natural death, a
suicide or an accident
The only exception is when a person dies while under the care of a doctor and had a
condition that was understood to be terminal
Two reasons why:
1. Determine whether a crime has taken place
2. To provide closure for the family
Began in 900 A. D. when coroners (called crowners) were first appointed by the King
Crowners were knights and usually wealthy landowners who were elected for life
o Examined the bodies of the deceased
o Held inquests
o Arrested the person or persons who were responsible for causing the death
Coroners today, still hold inquests, but they do not usually relate to a criminal
o Conducted after an accident or unnatural death
o Provide recommendations to attempt to prevent further deaths
After the Norman Conquest of England (1066), the coroner was responsible for
determining whether the decedents were Saxon
o Saxons not pleased by Norman takeover so were inclined to kill of any Normans
o The Normans introduced the “lex murdrorum” or “law of murder” which
implemented a fine on the whole village if a Norman was found dead
o The law considered any dead body be Norman, even if the person who died was
o In order to avoid tax, the village had to prove that the person was Saxon
Over time, coroners’ duties developed into the investigation of sudden, unexpected
natural deaths/violent deaths
o In Cananda, coroners were responsible for investigating sudden deaths
Coroner system brought to US in the 1600s
o The coroner was also the sheriff
1877: The Commonwealth of Massachusetts developed the medical examiner system
o Stated the death investigator had to be a physician
o In Canada, most provinces have coroner systems except AB, MB, NS and NL,
which have medical examiner systems
 ON has a coroner system, but their coroners must be physicians which is
not true of other coroner systems
The Five Main Questions in a Death Investigation
Who died?—What is the identity of the decedent?
Where did they die?—Was it where they were found or somewhere else?
When did they die?—What was the time and date of death?
Why did they die?—What was the medical cause of death?
How did they did?—What was the manner of death? Natural, suicide, accident or
The coroner/medical examiner has jurisdiction over the body even though the police are
the first responders at the crime scene
Type of Death
o If the death is suspicious
 The police/coroner/medical examiner will work together to
• Secure the scene
• Bring in homicide detectives
• Identification officers etc.
 The coroner/medical examiner’s role is to assist the police in their
criminal investigation
o If the death is not suspicious
 The role of the police is to assist the coroner or medical examiner’s
 In some provinces, the Coroners Act/Medical Examiners Act gives
authority to the police to act as medical investigators at the scene