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Forensic Science Midterm
Week 1:
Death certification in Canada falls under provincial jurisdiction
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Certificate requirements vary from province to province
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• Coroner System- the Coroner is a medical doctor who has received specialized death
investigation training
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• Medical Examiner System- A Medical Examiner is medical doctor who is received
specialized training to become a forensic pathologist
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Mission Statement
The office of the Chief Coroner of Ontario serves the living through high quality death
investigations and inquests to ensure that no death will be overlooked, concealed or ignored
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In Ontario, cases that fall under the jurisdiction of the coroner include:
• Sudden or unexpected deaths
• Deaths occurring to those in custody, in homes for the aged, in rest homes and other
institutions
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• Deaths from violence
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• Deaths resulting from disease or sickness which was not treated by a legally qualified
medical practitioner
Dr Michael Pollanen is the Chief Forensic Pathologist of Ontario
• The OFPS (Ontario Forensic Pathology Service) was created in 2009 following amendments
to Coroners Act
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Together, the Chief Forensic Pathologist and
Chief Coroner provide dual leadership for the death Investigation system in Ontario
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This is the fashion in which the cause
of death came to be
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"Necropsy" is from the Greek
for "seeing a dead body"
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The body is received at Pathology Unit or hospital in a body bag or evidence sheet
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After the body is received, it is first photographed
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Next, any evidence such as residue, flakes of
paint or other material is collected from the external surfaces of the body
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Samples of
hair, nails etc
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At this point, a general description of the body is made
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) *the deceased must first be identified:
External Examination:
• Bruises - injuries that do not break the skin; show discoloration of the skin
• Abrasions - the rubbing away of skin by friction
• Stab Wounds
• Lacerations - a torn ragged wound
• “Clean Cuts”
• Sharp Force Injuries
• Gunshot Wounds - entry wound (small circular wound) and exit wound (large with
intermingled tissue)
• Strangulation - abnormalities in trachea
• Fractures – simple and compound
TIME OF DEATH
• Rigor mortis (the stiffness of death) refers to the state of a body after death, in which the
muscles become stiff
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Rigor mortis occurs due to changes in the physiology
of muscles when aerobic respiration ceases
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(Approximately one hour after death and also disappears
after 36 hours)
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Body
Temperature drops about 1 ½ degrees per hour for the first 8 hours
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clothing, lightning or electrocution may affect the
temperature calculations
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The
essence of the pathologist's job is to use his or her skill and experience to determine the true nature
and cause of a particular wound
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• NOTE: Firearm Injury - A firearm causes a special kind of blunt trauma
• Sharp Force Injury -Sharp Objects Produce Incised Wounds
• Blunt Force Injury -Blunt Objects Produce Lacerations
• Contusion or bruising-accumulation of blood in tissues outside the blood vessels--usually
caused by blunt impact
• Hematoma-a blood tumor (contusions with more blood)
Autopsy Procedure:
• The pathologist first examines the outside of the body
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An autopsy table is waist-high stainless steel with
running water to facilitate washing away all the blood that is released during the procedure
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• The first cut known as the 'Y' incision is made
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The tail of the Y extends from the
sternum to the pubic bone and typically deviates to avoid the navel
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The skin from this cut is peeled back, with the top flap pulled over the face
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The brain is
then either cut fresh or is placed in a 20% solution of formalin to fix it for future analysis
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There is almost no bleeding, since a dead body has no
blood pressure except that produced by gravity
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The
stomach is cut open on its greater curvature and the contents are examined
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Finally, all major blood vessels are cut
open and examined lengthwise
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skull fracture
Mechanism of Death - the actual physiological change that causes life to stop
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Forensic Science Midterm
Classification of Traumatic Deaths
• Mechanical - sharp or blunt (firearm injury)
• Thermal - excessive heat or cold
• Chemical - poisons or drugs
• Electrical - electrocution or Lightning
Week 2:
Trier-of-Fact: The party that makes the decision of guilty or not guilty in a trial
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Jury Trial: Trial where the trier-of-fact is the jury
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• Jury listens to evidence presented and are instructed by judge as to the applicable case law
• Apply law to facts and evidence of the case and reach a decision of guilt or innocence
Admissibility of Evidence
• The determination of what matters may come before the trier-of-fact
• Rules of evidence seek to protect the jury from hearing evidence that is prejudicial,
irrelevant, time wasting, unconstitutional or unreliable
• Major rule that applies to all evidence, it must be relevant and competent
• Relevant: A condition of admissibility of evidence
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• Material means the evidence has something to do with the case being tried
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A set of legal constraints on the admissibility
of evidence
• Prejudice (evidence cannot unduly prejudice trier-of-fact; i
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prior convictions)
• Constitutional constraints (prohibit unreasonable searches of people and places; search
warrant is required)
• Statutory constraints (privileges btw Dr
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It is a hearing to determine the admissibility of certain
evidence (or the competency of a witness)
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USA
Federal Rules of Evidence (FREs) – FRE 702:
• If scientific, technical, or other specialized knowledge will assist the trier of fact to
understand the evidence or to determine a fact in issue, a witness qualified as an expert by
knowledge, skill, training, or education, may testify thereto in the form of an opinion or
otherwise if (1) the testimony is based upon sufficient facts or data, (2) the testimony is the
product of reliable principles and methods, and (3) the witness has applied the principles and
methods reliably to the facts of the case
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C
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Canada - R v MOHAN (1994)
Leading Supreme Court of Canada decision on the use of experts in trial testimony
• Dr
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Defense planned to call a psychiatrist as an expert on sexual assault
who was to testify that the culprit of the offence possessed abnormal characteristics
(pedophile and sexual psychopath) that Dr
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This evidence was held to
be inadmissible by the judge
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Relevance (probative value cannot be outweighed by prejudicial effect)
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Absence of any exclusionary rule
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Lay (non-expert) witness – may only testify to matters the he/she personally experienced
with 5 senses (what they saw, heard, smelt, tasted, felt)
2
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In Canada,
the use of a polygraph is sometimes employed in screening employees for government
organizations
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v
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The polygraph unit provides testing services and expertise in interview, interrogation and statement
analysis to police services
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The nerves can take one of two different paths to organs in our body
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• Note: These two systems act in opposition to one another, like the Brakes and Gas pedal
in a car
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• The parasympathetic system is active after the stress is over allowing the body to wind down
& rest: functions such as digestion, slowing heart rate & blood pressure
• Therefore the polygraph measures changes in the sympathetic nervous system!
A polygraph instrument is basically a combination of medical devices that are used to monitor
changes occurring in the body
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The Polygraph measures:
• 1
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P
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respiratory rate-pneumograph tubes fastened around abdomen & chest
• 3
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• Stimulate the subject to react
• Interpret the charts
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This may last about 1 hour
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It assesses the suitability of the subject (i
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physical ailments, low
intelligence, and use of medication)
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Design questions - The examiner designs questions that are specific to the issue under investigation
and reviews these questions with the subject
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The examiner asks 10 or 11 questions, only three of four of
which are relevant to the issue or crime being investigated
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LINES of Questioning:
Originally, lies were “detected” using a procedure termed the R/I (Relevant/Irrelevant) procedure
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The notion was that guilty or lying subjects would show much stronger emotional
reactions to relevant than to irrelevant questions, whereas innocent suspects should not
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Polygraph procedures were revised in the 1940s as the result of a man named John Reid, & his
Control Question Test (CQT)
• Uses control questions that are designed as a stimulus for the truthful subject
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The GKT (Guilty Knowledge Test)
• Important knowledge has not been disclosed to the public and only the perpetrator would
know about it and would react to it
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• In all cases, the reading of polygraph results is still more of an art than a science, and
different experts may differ in their analyses
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Common Countermeasures:
Often, people who are being given a polygraph exam will employ certain countermeasures in an
attempt to beat the instrument
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Examples include: Sedatives, Antiperspirant on fingertips, Tacks placed in the shoe, &
Biting tongue, lip or cheek
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A subject may attempt to have the same reaction to every question so that the examiner cannot pick
out the deceptive responses
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The scores range from +3 (strong
reaction to a control question) to -3 (strong reaction to a relevant question)
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This scoring is called the “Seven
Position Scale”
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Validity
“Notwithstanding the limitations of the quality of the empirical research & the limited ability to
generalize to real-world settings, we conclude that in populations of examinees such as those
represented in the polygraph research literature, untrained in countermeasures, specific-incident
polygraph tests can discriminate lying from truth telling at rates well above chance, though well
below perfection
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Work continues to find a better lie detector, and
things other than physiological measures are also being examined (posture, voice inflection, etc
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What is a drug?
• A drug is a natural or synthetic substance that is designed to produce a specific set of
psychological or physiological effects on the human body or other animals
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Licit Drugs - are manufactured to have specific, reproducible, predictable, beneficial effects on
the human body
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• Non-prescription drugs e
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Tylenol
• Prescription drugs e
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Oxycontin or oxycodone
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Forensic Science Midterm
2
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• E
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Oxycontin, heroin, LSD, Cannabis
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• There are 4 processes:
• ABSORPTION-how drugs are introduced into the body
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• Effects can be rapid or prolonged depending upon the route of absorption and the how
the drug is formulated (i
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some are sustained release)
• DISTRIBUTION- Involves the mechanisms by which drugs get to their site of action
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• METABOLISM-The process whereby a drug or other substance is chemically changed
to a different form, called a metabolite
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Other forms of elimination include respiration and perspiration
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• ABUSE: drug abuse occurs when people take drugs for purposes other than for which
they are intended
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It includes high temperature, physical
discomfort and could be fatal
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Therefore, increasing doses are necessary to achieve an equivalent psychoactive effect
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Drugs work together to
magnify effects or create effects that would not have occurred otherwise
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• What effect that level will have on a person?
• Alcohol – Could the level cause impairment of driving ability
• Could the level render a person unconscious – e
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sexual assault case
• Could the level cause intoxication – resulting in a person stumbling along a highway
and into the path a motor vehicle
• Drugs:
• Could the level cause death?
• Could the level cause impairment – driving, drowning cases
• Is the level – therapeutic? i
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No toxicity
• Drug interactions - some drugs taken together can result in a mixed drug fatal
intoxication
• Alcohol is a central nervous system depressant
• It slows your brain down
• Alcohol at low concentrations for most people is a feel good “drug”
• At high concentrations it is a poison!
• Alcohol + any other central nervous system depressant = potential death
DRUGS OF ABUSE
• 2 types:
• Licit drugs – prescription/non-prescription drugs
• Opioids – morphine, oxycodone, methadone, fentanyl , codeine - pain killers
• Non-prescription - dextromethorphan – cough syrup, diphenhyramine - Benadryl
• Illicit Drugs: sub categories of illicit drugs
• Stimulants: cocaine, methamphetamine, amphetamine, MDMA, MDA
• Narcotics: Heroin
• Hallucinogens: LSD, PCP, certain kinds of mushrooms
• Cannabis
Other types - new emerging drugs of abuse
• Synthetic Cannabinoids
• "Spice" refers to a wide variety of herbal mixtures that produce experiences similar to
marijuana (cannabis) and that are marketed as "safe," legal alternatives to that drug
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Some users report psychotic effects like extreme anxiety, paranoia,
and hallucinations
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Post mortem interval (PMI) is the time that has elapsed since a person has died
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For
example:
• Algor mortis (body cooling), Rigor mortis (stiffening of limbs)
• Vitreous humour-eye fluid changes
• Entomology
• State of decomposition
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Forensic Science Midterm
Forensically important conclusions may be drawn by analyzing the phase of insect invasion of a
corpse or by identifying the life stage of the necrophagous insects found in, on or around the body
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Knowledge of insect biology and habitats may provide
information for accurate estimates of how much time a body has been exposed to insect activity
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Maggot Mass Effect -The mass of maggots can cause a local increase in temperature
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This temperature can be well over 100 degrees F (37 degrees C) and may be
at or near the lethal high temperature for a species
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NECROPHAGES -the species that feed on corpse tissue
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These are of the order Diptera di - two, ptera – wings
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Chemicals are by-products of
decomposition
• 2
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Large populations of these may slow down decomposition of the corpse
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The Life Cycle of Fly:
• Three developmental stages called instars
• Maggot increases in size dramatically at each stage
• Blow fly larva forms from egg 8 hours after egg is oviposited
• Second instar forms 20 hours later
• Third instar stage forms 20 hours after that
• After 5 days, larva stops feeding and rests
• After a few days, larva becomes a pupa
• Adult fly emerges 3 weeks later
Time it takes to go from egg to adult varies greatly
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Many other factors
affect number and timing of successive generations of necrophilious (“dead loving”) insects: i
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Location, shade, slope, where the body lies
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The
maggot mass temperature will vary with the size of the mass, the stage of insect development & the
location on the corpse
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Note: Blow flies neither fly nor lay eggs at night (after sunset)
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They will become active
only if temperatures are above 50F
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A minimum and maximum time since death can be determined based on the insect evidence
collected and developed
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Two Different Methods of determining PMI using insects:
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Forensic Science Midterm
•

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METHOD 1 Based on the period of time required for a given species of insect to reach a
particular stage of development *1st few hours-several weeks
• The pattern of development or rate of growth is primarily influenced by two things: the
species of fly (since flies are usually the first ones immediately attracted to the body
after death) and the temperature of the environment/scene (as it increases, rate of
development increases and vice versa)
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For example, based on laboratory studies of P
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2 hours) to emerge
from its egg
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METHOD 2 Based on successional colonization of the body by a sequence of carrion
insects *1st few weeks-dry bones
• The basic concept of ecological succession is that any unexploited habitat, in this case, a
corpse, will be invaded by a series of different organisms
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This
alteration will serve to make the habitat attractive to a second wave of organisms which
will, in turn, alter the habitat for use by yet other organisms
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Richard Merritt discovered super maggots on a corpse
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)
Collection of climatological data from the scene
• Ambient air temperature
• Ambient humidity
• Ground surface temperature
• Body surface temperatures
• Below-body temperatures
• Maggot mass temperatures
• Post-body removal sub-soil temperature
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Forensic Science Midterm
Collection of specimens from:
• The body before its removal from the scene
• The area surrounding the body (up to 20′) before its removal
• The area directly under the body after the body has been removed
• Necrophilious insects are attracted to dark, moist areas: face, (eyes, ears, nose), genital
areas if exposed and open wounds, etc
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• Crawling insects can be collected with forceps or fingers
• Eggs, a mixture of larvae of various sizes, and any adults should be collected
• Soil under body should be sampled
NOTE: Some insects will be placed in a Killing Jar which is a wide mouth jar containing cotton
balls soaked in ethyl acetate
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Samples of recovered insects are processed in two ways:
• Live Samples - are grown to full term and used for identification
• Preserved Samples (in Ethanol) - “Stop the clock” to show the stage of growth/development
on the corpse
Classification of insects on body can only be performed by an experienced forensic entomologist
with the proper reference collections
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Science of
identifying and classifying organisms is
called taxonomy
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Anthropology is the study of humans
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Forensic anthropology is the
application of the study of human skeletons (& their identification) to matters involving the public
and the law
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It is an Active organ system (Bone can add or subtract
boney material as needed over time, as a response to stresses)
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• Bone growth and maintenance are complex processes that occur at micro/macroscopic levels
• Ossification is the process of bone formation, in which connective tissues, such as cartilage
are turned to bone or bone-like tissue
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BONE GROWTH
A long bone, such as your femur (thigh bone), grows in length at either end in regions called growth
plates
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The new cartilage cells push older, larger cartilage cells towards the middle of a bone
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When a bone has reached its full size, its
growth plates are then converted into bone
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The Growth Plate is also known as an epiphyseal plate
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Collecting of Human Remains:
Scene of remains is treated & processed like a crime scene, an orderly and careful search that may
utilize various detection methods
Each bone fragment is flagged or marked
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They utilize archaeological techniques
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Damaged
remains may require reconstruction prior to analysis
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The Biological Profile
This is the process of identification of a skeleton
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NOTE: Class characteristics are characteristics that are common to a group of similar objects
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The object is unique
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Individual characteristics such as injury to a bone or unique dental work may also be
identified
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The appearance and fusion of the various epiphyses
throughout the body indicate stage development
Once growth ceases, (around age 25) only repairs and reactions to aging appear on the bones
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Pubic symphysis, or pubic “false joint,” is considered most
reliable estimator of age at death
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The smoother the surface of the pubic
symphysis the older the bone
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Is the Deceased Male or Female?
• Gender Differences in death are not always apparent
• Sexual differences in human skeleton begin before birth but are more diagnostic after
puberty
• “Gender should not be estimated unless individual is above 18 years of age
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Pelvis: Sciatic notch, is a useful trait for distinguishing sex
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Also, the pubic angle is narrower in males and wider in females
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Ancestry:
Is one of most difficult estimations in forensic anthropology? Designation of ancestry terms include:
White, Black, Hispanic, Asian, Native American, and Other
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)
Stature (A person’s height):
Living stature relates directly to the length of our long bones
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Stature determination involves measuring long bones and
using a mathematical formula to approximate height
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Individualization of Human Bone
• Bone trauma and individual features of bone assist in identification
• Signs of broken bones or trauma show up on X-rays and remain throughout life
Facial Reproductions: Two Methods of Analysis of Skulls
1
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Computers and videotaping may also be used
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2Three dimensional reconstruction of soft tissues on face on found skull is done
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It also includes the presentation of expert evidence in a court of law
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Postmortem records are carefully charted;
contain written descriptions of the dental structures& radiographs
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Fillings, caps & restorations play a
large role in identification process
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Differences between x-rays taken before death and after death must be explainable
Why is dentition important in forensic science?
• Teeth are made of enamel, the hardest substance that the body produces, therefore can
survive severe conditions
• Teeth interact with environment and reflect the conditions a person experienced during life
Tooth Development
• Each tooth has three parts: crown, body and root
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• Teeth grow from chewing surface, or cusps, downward to the roots
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Identification of dental remains:
• Burning, drowning, fire, explosion or decomposition cases may require identification of
victim by their teeth
• Prior dental records must exist for matching
• Comparison of post mortem and ante mortem dental records can confirm the conclusion
The goal is individualizing a set of human remains, in other words getting a “positive
identification”
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BITE MARKS - on the body of victim can be compared with a cast of the suspect’s dentition
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Alcohol Impaired driving:
• What is impairment with respect to driving?
• Impairment – simply is a decreased ability to do a task
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The brain functions most sensitive to the effects of alcohol include divided
attention, information processing, tracking (keeping your car in the proper lane) and reaction
time
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• Alcohol decreases your ability to control risk taking
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• In a study looking at the risk of being involved in or causing a fatal motor vehicle crash, at
blood alcohol concentrations ranging from 50 to 79 mg/100 mL, the relative risk of driver
fatality increased to approximately 3
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• The criminal code legal limit is 80 milligrams of alcohol in 100 millilitres of blood
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The more you drink, the higher your
blood alcohol concentration will be which leads to a greater degree of impairment
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• A seasoned drinker does not become tolerant to the sensory, cognitive, motor impairing
effects of alcohol
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• INTOXICATING EFFECTS OF ALCOHOL:
• This is what most people think or believe impairment is!
• Intoxicating effects of alcohol include : initial feel good feelings, relaxation, mental
clouding, dis-inhibitory effects, slurring of speech, vomiting , muscle incoordination,
confusion, drowsiness, unconsciousness, death
The role of the forensic toxicologist in impaired driving cases:
• Teach police officers in the theory and operation of the approved screening devices and the
currently used Intoxilyzer 8000C approved breath testing instrument
• Analyze blood and serum samples from drivers suspected of being impaired by alcohol
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Forensic Science Midterm
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•

Prepare reports regarding what a person's blood alcohol concentration would be at the time
of being stopped by the police or at the time of an accident, provide opinions regarding the
impairing effects of alcohol
Testify in court

Drug impaired driving
• Drug impaired driving is a significant public health and public safety problem in the United
States and abroad, as documented through a growing body of research
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• The Drug Evaluation and Classification (DEC) program is designed to detect a drug
impaired driver and classify the categories of drugs present in his or her system
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• The DEC program breaks down detection into a twelve step process that Drug Recognition
Expert (DRE) can use to determine the category or categories of drugs that a suspect is
impaired by
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