all forensics

corpus delicti

corpus delicti

body of the crime

modus operandi

mode of operating (M.O.)

macrosopic crime scenes

eg. house

microscopic crime scenes

eg. room in a house

physical evidence helps…

• links between persons, scenes, and objects

• idenification of suspects

• identification of unknown substances

• reconstruction of crime

• leads

• corpus delicti

• modus operandi

crime scenes require management of…

info

manpower

technology

logistics

first responding officer

police, medical personnel, or fire department usually first to arrive

crime scene security measures —>

• assist victim

• search for suspect

• detain and separate any victims

• secure crime scene

• make crime scene log

crime scene survey

investigator will…

• perform preliminary scene walk thru

• note transient or conditional evidence —> requires immediate protection/processing

• weather conditions

• note points of entry/exit/travel paths

transient evidence

evidence that only lasts for a short time

eg. foot prints in snow, blood drops on a sidewalk when it’s raining

crime scene documentation

crime scene must be documented for permanent record before processing

4 tasks of documentation:

• note taking

• videography

• photography

• sketching

note documentation

• who what where when why

• notification information

• arrival information

• scene description

• victim description

• crime scene team

videography doumentation

video should

• follow scene survey

• exclude crime scene members + equipment

• exclude any narration

—> provides accurate impression of crime scene

sketching doumentation

• final task

• for recording accurate measurements

  • triangulation

  • baseline

  • polar coordinates

• techniques indentify 2 fixed/starting points in which measurements are compared to

search methods

• link —> one evidence type leads to another

• zone

• line/strip

• wheel/ray

• grid

• spiral

searches rules

• important items are not touched or moved during search

• items r marked without alteration

• items documented before and as they are moved

collection of physical evidence

• after documentation and search

• evidence collector —> collects packages, marks, seals and preserves

• if more evidence is found after something is moved, immediate documentation is followed

preservation of physical evidence

• packaged in primary container then placed into secondary container

• large pieces of paper used to fold aroudn large item to secure trace evidenve (ie. pants iwth traces of hair)

crime scene reconstrution

determinating events that could’ve occured —> thru analysis of location and position of evience and apperance of crime scene

crime—> collection of evidence —> conjuncture (beginging of hypothesis) —> hypothesis —> testing of data (lab testing —> reconstruction theory) —> data collection —> event

forensic pathologist

physicians specialing in pathology (diagnosis of disease) —> completing autopsies —> determine cause and manner of death

cause of death

underlying medical condition, disease or injury that begins a lethal chain of events resulting in death

mechanism of death

biochemical or physical thing caused by the cause of death that lead them to die

manner of death

way in which a death occurs —> Homicide, Suicide, Accidental, Natural or Undetermined

livor mortis

dicolouration of body

(occurs by settling of red blood cells after blood stops circulating)

• seen after a few minutes

algor mortis

cooling of body after death

rigor mortis

stiffening of muscle that occurs ~4 hrs after death

(chem reaction —> glycogen not reformed)

inframammary incision

T shaped incision

from shoulders to lower chest
from shoulder to top of pubic bone

organs r removed and weighed and dissected to determine disease or injury

examination of brain

back of ear to ear, peel scalp backward, saw skull in circular motion, remove skull cap

autopsy documentation and speciemen

• photos required

• pathologist collects sampels for other specialist

• blood taken from large veins (aorta)

• blood and urine used to find drugs or abuse

• small portions of internal organs preserved

• preserve speciemen for DNA analysis

traumatic deaths

can be —> natural, homicidal, suicidal, accidental

classified as —> Electrical, thermal, chemical, mechanical (sharp force, blunt force —> non-firearms and firearms)

penetrating (stab wound or gunshot wound) or non-penetrating (falls, motor vehicle collisions)

mechanical trauma

sharp objects —> incised wounds

blunt objecets —> lacerations

cause death by exsanguination (bleeding to death)

blunt force trama

most commonly causes death if damage to brain

gunshot wounds

peforating gunshot wonud —> both entrance and exit wound

penetrating gunshot wound —> entrance only, bullect recovered in autopsy

contact gunshot wound

gasses blacken skin, bright red from chemical reaction, various lacerations (gas blown into wound)

intermediate range gunshot wound

only unburned powder + bullet enter skin (no gases) —> stippling/tattoing around bullet hole

distant gunshot wounds

only bullet (no gas/smoke or unburned powder) —> circular wound with scraped skin rim, lacerated exit wounds

other blunt force trauma

motor vehicle collisions

homicidal requires lethal head injuries

blunt force trauma to head —> lotsss of bleeding —> mechanism of death is drowning in blood that apsritates into lungs

contusion

bruise

hematoma

super bad bruise —> swelling and stuff too

central nervous system depressant (chemical trauma)

increasing degrees of coma —> stop breathing —> leading to death

• alcohol

• barbiturates (sleepy bye bye, barbiturate acid)

• benzodiapines (sleepy + hypnosis, eg. Xanax)

• opiates

central nervous system stimulants (chemical trauma)

results in super high temps, seizures and quivering of the heart

cocaineeee

- Jake

other chemical trauma

CO poisoning (common in A, S and H deaths)

thermal trauma

hypothermia —> cold

hyperthermia —> hot

—> they breakdown body temp mechanisms

fire —> causes death from complications after or from smoke

electrical trauma

different mechanism:

ventricular fibrillation —> low voltage, quivering, can’t save u bro

defibrillation —> high voltage, tetany (sustained contraction)

poration —> causes loss of limbs

asphyxias

interruption of oxygenation to the brain

• strangling (manual or by ligature)

• drowning

• thermal

• chemical

Forensic science

Science techniques applied to judicial system

• interpreting/examining criminal evidence

Arose from

• Chem, bio, medicine, pharmacology

Recognizable by mid 1800s

Death investigation

Generalists

Many forensic disciplines

specialist

one forensic field

Eg. Toxicology, pathology

Victor Balthazard

(1852-1950) (French)

Medical examiner for Paris

Advance analysis of firearms and hair samples

• photographic method to indentify/compare distinct markings on different firearms and bullets

Probability models —> uniqueness of fingerprints (10^60)

Alphonse Bertillon

(1853-1914) (French)

Bertillonage identification technique —> identify suspects and criminals

• 11 busy measurements w/ info and visuals stored on a card

Replaced in the 1900s by fingerprinting

Sir Francis Galton

(1822-1911) (English)

First fingerprint classification system

Classify patterns —> loop, arch, whorl

Dr. Calvin Goddard

(1891-1955) (American)

Scientific examination of firearms evidence in US

Hans Gross

(1847-1915) (Austrian)

“Criminalistics” —> forensic analysis of evidence

holistic view

Edmond Locard

(1877-1966) (French)

Locard’s exchange principle —> every person-person or person-place contents results in the transfer of materials between them

Microscopic trace evidence

Mathieu Orfila

(1787-1853) (French)

Founding father of forensic toxicology

Study poison, mostly arsenic —> detect in tissues, blood, other fluids

Sherlock Holmes

Fictional —> Arthur Doyle

Shaped public image of forensics

Scientific Method

1. Formulate hypothesis

2. Test hypothesis (observation or experiments)

3. Revise hypothesis

4. Repeat 1-3 until data aggressors with hypothesis

Collect facts —> relationships—> hypothesis—> testing methods

Adversarial system

Lawyers represent one of two positions arguing for cause

contrite failbilism

awareness of how much we don’t know and acknowledging the possibility of making mistakes

“just so yk i might be wrong idk”

civil cases

between individuals or parties

criminal cases

involves government charging party violating criminal law

prosecution (plaintiff) —> files criminal charge

defendant —> accused

trier of a fact

comes to decision based on evidence

eg. jury, judge, grand jury

felonies —> serious case

misdemeanours —> minor offence

subpoena

document that states details of trial

voir dire process

scientist decribes their qualifications

prosecutiorial bias

when scientist seeks out results that support their agency/role

frye standard

jurisdiction

• requires new methods —> rejected the validity of the polygraph test —> led to general acceptance criteria

daubert standard

rial judge responsible for determining if the evidence is relevant an if testing methods are valid/reliable

determine if evidence is valid —> gatekeeping —> strats inclse general acceptance, falsability of theory etc

daubert trilogy

daubert vs merrel dow pharmacutical

joiner case —> science data must pass daubert criteria and relvance test

kumho tire case —> entended daubert ruling to all experts

inculpatory evidence

show’s person’s involvement in an act

exculpatory evidence

exludes person as a source

direct evidence

directly estalish fact —> ie eye witness at bank robbery

circumstantual evidence

trier of fact has to infer —> all forensic evidence is circumstantual

eg. blood was found at the crime scene and it matched with the defendant’s blood in a DNA test

reconstruction evidence

provides info on what happened before, during or after crime

associative evidence

reconstructing a crime scene —> associating or disassociating someone to a crime scene —> eg. hairs prints etc

class-characteristic evidence

doesn’t link to a suspect

eg. this bullet belongs to this type of gun

individual characeristic evidence

links to a suspect

eg. matching prints, fibers etc

biological evidence

a scientific group

human tissue or fluids —> used to indentify or DNA test

chemical evidence

a scientific group

drugs, toxins, expolsives etc

trace evidence

a scientific group

items left behind at crime scene (locard’s exchange theory)

questioned documents

a scientific group

handwriting comparasions, alterations, obliterations, ink/paper characteristics

fingerprint evidence

a scientific group

print development is achieve chemically, physically or photographically

impression evidence

a scientific group

eg. footwear, tire prints etc

firearm and tool mark evidence

a scientific group

type of impression evidence —> eg. cartridge casings, shells, fired bullets

excultionary evidence

meant to filter out inapproiate/irrelevant information presented by other side