FRSC2030 MIDTERM

the three main types of evidence and examples

1. physical (objects, impressions)

2. observations/conditions (weather, presence of lights)

3. testimony (eye witness, expert)

locards principle

every contact leaves a trace (leaving something behind or taking something away)

identification

determination of the physical or chemical identity of a substance

comparison

subject specimen and standard/reference to the same tests and exams to find whether or not they have common origin

best evidence rule

collect and submit original evidence when possible

how is trace evidence collected

1. forceps

2. tweezers

3. by hand

4. tape life

5. vaccum

trier of fact

judge or jury

mohan legacy

admission of expert evidence depends on relevance, necessity is assisting the trier of fact, and a properly qualified expert.

daubert legacy

1. trial judge must ensure testimony is relevant and reliable

2. focus on principles and methods, not conclusion

forensic entomology and primary focus

study of insects in relation to legal investigations with a primary focus to estimate elapsed time since death

when, what, how (forensic entomology)

when - time since death

what - insect species present

how - insect colonization pattern

insect evidence shows…

1. if the body has been moved to a second site after death

2. if the body has been disturbed after death

3. presence and position of wounds when they are no longer visible

4. abuse and neglect

when to use either forensic entomolgy method

maggot age and development - death has occured less than a month prior to discovery

successional waves - corpse has been dead for a month to a year

maggot age and development

1. maggots lay egg in corpse (orifices or natural holes)

2. egg hatches into first instar / larvae

3. larvae feeds on corpse

4. second instar, then third instar

5. third instar larvae eventually stops feeding and wander away into clothes or soil before it pupates

6. adult fly emerges and cycle repeats

how does temperature affect maggots

as temperature increases insects develop faster and vice versa

successional waves of insects

1. different stages of decomposition are attractive to different species of insects

2. some arrive rapidly at presence of blood or other bodily fluids while some are not interested in a fresh corpse

3. insect assembalage can be analyzed to estimate a window of time in which the death took place

where to collect insects from

1. clothing

2. soil

3. carpet

how to collect and preserve blow fly eggs

1. collect with paint brush dipped in water or forceps

2. preserve half in 75-95 alcohol or 50 isopropyl

3. place the other half in a vial with a little damp paper towel

important factors about the death site for forensic entomology

1. habitat (vegetation, soil, weather, temperature and humidity, coordinates)

2. remains (clothing, covering of body, blood or other fluids, cause of death, wounds, drugs, position, stage of decomposition)

why are maggots and pupae raised

1. larvae are very difficult to speciate but adults have more diagnostic features

2. the dates of pupation and emergence are used to calculate age at time of collection

how are insects used for neglect cases

insects will colonize on a living person, onset maggot infestation in children will give minimum time interval since childs last diaper change

limitations of forensic entomology

1. bodies are rarely found under weather station but temperature of death site is important

2. seasonal in canada

3. freezing

4. deep burial

5. secure wrapping

basic tenent of science

1. no theory can ever be proven to be true

2. theories can only ever be disproven

3. the more often you can not disprove a theory, the more likely it is true

forensic method

systematic approach to documenting, collecting, and interpreting evidence for presentation in court of law

weight of physical evidence is ultimately determined by…

the court

what is the role of the triers of fact (judge/jury)

use evidence to determine guilt, liability, or damages

role of a regular witness in court

relate what they did, saw, or heard to the case at hand while under oath

role of an expert witness in court

educate the trier of fact by using layman terms in explaining and interpreting evidence

direct examination

questioning of witness conducted by party who called them to testify

cross examination

examination of witness by opposing party to test or develop the truth of evidence given during direct examination

requirements of an expert witness

1. greater knowledge of skill than trier of fact

2. knowledge gained through study, experience, or observation

requirements for admission of expert evidence

1. relevant

2. necessary to assist trier of fact

3. absence of exclusionary rule (prohibited by statute)

paradox of experience

a forensic scientist is susceptible to contextual influence since they’ve seen it all (confirmation bias)

foundational validity

discipline based on research and studies that are repeatable and reproducible

applied validity

reliably applied in practice (known method)

necessary for typical autopsies

1. body relatively intact

2. presence of soft tissue

unable to perform typical autopsies on…

1. badly burned bodies

2. severely decomposed bodies

3. bodies in pieces

what is included in a biological profile

1. sex

2. age

3. stature

4. ancestry

importance of sex assessment

1. narrow down identification scope

2. other three assessments are dependent on sex

features of sexual dimorphism for humans

1. males are taller, heavier, and wider

2. females have biomechanical needs for childbirth (differences in pelvis shape)

sex-metric method

evaluate size and robusticity of bones by placing measurements into formula and comparing them

age estimation method

1. examine bone porosity, density, and specific types of newly formed bone

2. using knowledge of how bone changes over time

important areas for age estimation

1. dentition

2. pubic symphysis

3. auricular surface of ilium

4. sternal rib ends

ancestry estimation method

skeletal characteristics linked to ancestral groups, frequency of variations between groups

stature estimation method

1. extrapolated for the length of the long bone (tibia, humerus, femur)

2. y = m(x) + b / stature = m(femur) + b

why is identification important?

1. legal matters (wills, spouses, remarrying)

2. emotional matters (closure, appropriate burial)

3. investigation matters (86% of homicide victims know their killer, homicides are rarely solved if the victim is unknown)

comparitive data that helps with identification

1. missing persons list

2. medical or dental records

3. DNA samples

positive identification

no other person could possibly share those features

assists in making a positive ID

1. DNA

2. frontal sinus patterns

3. cranial suture patterns

4. surgical hardware with serial number

5. dentition

incisors

blade-like teeth of the anterior dentition used for cutting, each jaw contains four

canines

conical teeth distal to the incisors used for grabbing, each jaw contains two

premolars

two-cusped, transitional teeth between the canines and molars, each jaw contains four

molars

four to five cusped distal teeth used for grinding, each jaw contains six

odontogenesis

the process by which teeth develop within the jaws

human dental formula

2-1-2-3

a forensic odontologist…

1. uses dentition in the identification of individuals by comparison of victims teeth with antemortem dental records

2. analyzes negligence, standard of care, and injury in dental malpractice

forensic odontologist postmortem examination and record

1. whether teeth are present in a socket

2. whether teeth are filled or unfilled and the type of material used in filling

3. presence of false crowns

4. bridges and changes on dentitions due to gum or peridontal disease

trauma

physical disruption of living tissue by outside forces

alteration to bone

any change to physical property

where do fractures occur

the weakest part of the bone where applied force overcomes bone strength

factors of trauma

1. type (sharp, blunt, projectile)

2. number of blows and direction

3. amount of force

extrinsic factors of trauma

1. direction and position of body

2. magnitude

3. rate of force applied

4. loading types

if a fracture occured antemortem there is…

1. presence of healing

2. blunting (decreased sharpness)

3. reconnection of fracture egdes

4. new bone added (thick and porous)

if a fracture occured perimortem there is…

1. green/fresh bone response (discoloration in skeletal tissue due to putrefaction)

2. sharp edges

3. hinging

4. fracture lines

5. edges angled and jagged

6. blood staining

fracture repair

1. blood flows to injury site and clots immediately

2. connective tissue forms temporary callus and is replaced by woven bone / primary callus (approx 7 days after injury)

3. finally replaced by mature bone which is reshaped and reduced in size

features of blunt force trauma

1. slow loading force

2. relatively large area of impact

3. large area of bone affected

4. hammer, baton

types of blunt force fractures

1. radiating fractures (spread outward from POI)

2. circular concentric fractures (form around POI)

3. depressed fractures (cave in POI)

4. hinge fractures (horizontal break)

features of projectile trauma

1. rapid application of force

2. relatively small surface area

3. force affects size of wounds

4. gun, shrapnel

characteristics of projectile injuries

1. ring/cone crack (upside down triangle)

2. beveling (concave shape at bullet entrance, gives bone spongy appearance)

3. round

characteristics of projectile entrance wounds

1. circular defect

2. keyhole defect

3. sharp external edge

4. internal beveling

5. radiating fracture (spread outward from POI)

characteristics of projectile exit wounds

1. various shapes

2. larger than entrance

3. jagged edges

4. external beveling

sharp force trauma

an alteration caused by a tool with a point or beveled edge

knife alterations

1. incisions

2. punctures

3. gouges

4. kerfs

penetrating nonincised alterations

1. awls

2. icepicks

3. chisels

4. screwdrivers

features of incised sharp force trauma

1. clean edge

2. longer than wide

3. cuts or slashes

4. often found on ribs, face, forearms, hands

features of chop marks

1. deep gouging wound

2. entry is smooth and flat or rough and fracturing

3. both blunt and sharp force trauma

4. done with a heavy instrument

kerf floor

point at which cut ends

penetrating

enter, no exit

perforating

pass all the way through

coroners act

law that sets out the jurisdiction, role, and powers of coroners

the coroners act states that it’s the responsibility of everyone to notify the coroner in cases of…

1. sudden and unexpected deaths

2. deaths that appear to be the results of an accident, suicide, or homicide

3. deaths in custody

4. deaths in nursing homes

5. deaths on construction sites

inquest

public hearing under authority of coroners act that informs the public about the circumstances of death and how to avoid future deaths

agents of change

1. changes in legislation (graduated licensing, labour laws)

2. policy (how police and courts administer change)

3. procedures (protecting children, safer medical practices)

4. product development (safety equipment in vehicles)

the goudge inquiry

inquiry into pediatric forensic pathology in ontario due to rising concerns over how criminally suspicious deaths involving children were being handled (dr. charles smith was woefully undertrained)

s. sherret case

sherret found son unresponsive, dr. smith mistook a normal gap between infant cranial bones as a skull fracture from smothering, sherret was jailed for infantacide

l. reynolds case

reynolds charged with second degree murder of his seven year old daughter after dr. smith claimed she has numerous scissor stab wounds, the charges were dropped when experts from both sides agreed that the injuries were from a dog attack

how do the coroner and the forensic pathologist work together

coroner - authority over the body and the final decision with respect for conduction autopsies

forensic pathologist - responsible for conducting autopsy

rigor mortis

muscles progressively stiffen due to a chemical reaction in muscle protein

livor mortis

blood in the body sinks under gravity, pooling in lower regions

visible externally on the skin as a dusky blue while other parts of the body under pressure will be pale

algor mortis

body cools slowly after death until core temperature equals environment (1.5 F an hour within first hour)

autolysis

body is decomposed by its own enzymes

putrefaction

body is decomposed by bacteria from within or on the surface

postmortem interval

warm and flexible (0-3 hours)

warm and stiff (3-8 hours)

cold and stiff (8-30 hours)

cold and flexible (over 30 hours)

cause of death

injury or disease that started biological chain of events resulting in death / medical reason for death (gunshot wound to the head)

mechanism of death

a biochemical or physiological abnormality produced by the cause of death that brought about the cessation of life (exsanguation)

manner of death

how cause of death came to be / circumstances surronding the incident that caused death (homicide)

indicators of suicide

1. presence of self-inflicted non-fatal injuries

2. wounds under clothing

3. weapon present

4. wounds at throat, wrists, ankles

5. no disfigurement

6. body unmoved

indicators of homicide

1. defensive wounds

2. wounds through clothing

3. no weapon present

4. usually injuries to vital organs

5. disfigurement

6. body moved

six forensic analysis questions

1. who (identify)

2. what (characterize, categorize)

3. when (time)

4. where (location)

5. why (motive, explanation)

6. how (mechanism, sequence)