FORENSIC SCIENCE

INTRODUCTION to

Crime Scene

Investigation

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CRITICALTHINKING

When Mrs. Jackson came back from lunch, there were several messages on her desk. By changing each digit of the phone numbers to one of the three corresponding letters on the telephone buttons, can you determine from whom each message came?

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Answers to Critical Thinking

336-8478 dentist(222)686-8268 accountant774-6837 printer487-2263 husband247-5463 airline832-2437 teacher

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Forensic Science

Definition: The application of scientific technology to supply accurate and objective information reflecting the events that occurred at a crime.

What does a Forensic Scientist DO???

1. Analyze physical evidence

2. Provide Expert Testimony

3. Provide training in the recognition, collection and preservation of physical evidence

Complex ReasoningIn Forensic Science

Deductive (reasoning from the general to the particular) and

Inductive Reasoning (reasoning from detailed facts to general principles)

Classifying Comparing and Contrasting Problem Solving Analyzing Perspectives Constructing Support Error Analysis

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Locard’s Exchange Principle

Whenever 2 objects come in contact with one another, they exchange some material (dust particles, hair, dead skin cells…)

Locard strongly believed that every criminal can be connected to a crime by dust particles carried from the scene

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Forensic Pathology

Investigation of sudden unnatural, unexplained or violent deaths

Answer the questions:Who is the victim?What are the injuries, when did they occur, and how

were they produced?5 manners of death: natural, homicide, suicide,

accident, undetermined

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Crime Scene Team

A group of professionals investigators, each trained in a variety of special disciplines.

Team Members First Police Officer on the scene Medics (if necessary) Investigator(s) Medical Examiner (if necessary) Photographer and/or Field Evidence Technician Lab Experts

pathologist serologistDNA expert toxicologistforensic odontologist forensic anthropologistforensic psychologist forensic entomologistfirearm examiner bomb and arson expertdocument and handwriting experts fingerprint expert

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First Officerat the Scene

A Assess the crime scene

D Detain the witness

A Arrest the perpetrator

P Protect the crime scene

T Take notes

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Eye Witness

“Perception is reality.”

As a result an eye witness may not be the best source of crime scene information.

A police composite may be developed from the witness testimony by a computer program or forensic artist.

(Eye Witness Activity) Faces Composite Programby InterQuest

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Crime SceneSearch Patterns

Spiral Grid

TWO of FOUR PATTERNS

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Crime SceneSearch Patterns

Strip or Line Quadrant or Zone

TWO of FOUR PATTERNS

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Crime SceneSketch

Date: August 14, 2001 Criminalist: Ann WilsonTime: 11:35 Location: 4358 Rockledge Dr

St. Louis, Mo.

A. Couch/sofa

B. Female body

C. Knife

D. Over turned Lamp

E. Chairs

F. Table

G. Fireplace

cD

E

EE

E

E

A G

F

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Physical EvidenceTransient Evidence--temporary;

easily changed or lost; usually observed by the first officer at the scene

Odor--putrefaction, perfume, gasoline, urine, burning, explosives, cigarette or cigar smoke

Temperature--of room, car hood, coffee, water in a bathtub; cadaver

Imprints and indentations--footprints; teeth marks in perishable foods; tire marks on certain surfaces

Markings

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Physical Evidence (cont)

Pattern or Transfer Evidence--produced by direct contact between a person and an object or between two objects.

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Physical Evidence (cont)

Conditional Evidence--produced by a specific event or action; important in crime scene reconstruction and in determining the set of circumstances within a particular event.Light--headlight; lighting

conditionsSmoke--color, direction of travel,

density, odorFire--color and direction of the

flames, speed of spread, temperature and condition of fire

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Conditional Evidence (cont.)

Location--of injuries or wounds; of bloodstains; of the victims vehicle;of weapons or cartridge cases; of broken glass, etc.

Vehicles--doors locked or unlocked, windows opened or closed; radio off or on (station); odometer mileage

Body--position; types of wounds; rigor, livor and algor mortis

Scene--condition of furniture, doors and windows; any disturbance or signs of a struggle.

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Evidence Characteristics

Class--common to a group of objects or persons

Individual--can be identified with a particular person or source.

ABO Blood Typing Blood DNA Typing

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Medical Examiner vs the Coroner

A medical examiner is a medical doctor, usually a pathologist and is appointed by the governing body of the area. There are 7 medical examiners in the state of Missouri and 400 forensic pathologists throughout the U.S.

A coroner is an elected official who usually has no special medical training. In four states the coroner is a medical doctor.

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Medical Examiner’sResponsibilities

Identify the deceased Establish the time and date of death Determine a medical cause of death--the injury or disease that resulted in

the person dying

Determine the mechanism of death--the physiological reason that the person died

Classify the manner of death Natural Accidental Suicide Homicide Undetermined

Notify the next of kin

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THE BODYRigor Mortis

Temperature Stiffness Time Since of body of body Death

•Warm

•Warm

•Cold

•Cold

•Not stiff

•Stiff

•Stiff

•Not stiff

•Not dead more than 3 hrs

•Dead between 3 and 8 hrs

•Dead 8 to 36 hours

•Dead more than 36 hours

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THE BODYLivor Mortis

Livor mortis is the settling of the blood, causing the skin to change colors.

Lividity indicates the position of the body after death. When lividity becomes fixed, then the distribution of the lividity pattern will not change even if the body’s position is altered.

Lividity usually becomes fixed between 10 and 15 hours after death.

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THE BODYAlgor Mortis

Algor mortis is body temperature.

Average human body temperature: 98.6 F (37 C)

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Time Frame of Death

Condition Appearance Periphery blood drying 30 min to 2 hrs Blue-green discoloration of skin

Right and left area of abdomen 24 hours Entire abdomen 36 hours

Bloating 36 to 48 hours Skin slippage 4 to7 days Absence of smell from bones more than 1 year

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Time Frame of DeathEyeball Changes

Condition Appearance Cornea drying (eyes open) minutes Cornea drying (eyes closed) 2 hours Corneal cloudiness (eyes open) less than 2 hours Corneal cloudiness (eyes closed) 12 to 24 hours Eyeball collapse more than 24 hrs

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One can die of a massive hemorrhage (the mechanism of death) due to a fall (cause of death) as a result of being pushed (homicide), jumping (suicide), falling (accident), or not being able to tell which (undetermined). All of which are manners of death.

THEREFORE,

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FACETS OF GUILT

Means--the ability of have committed the crimeMotive--the reason for committing the crime.

(This doesn’t have to be proven or presented in a court of law, but its what everyone wants to know.)

Opportunity--time or availability to have committed the crime.

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Just A Thought

It’s not what you know that hurts you, its what you think you know and it’s not so . . . . .Mark Twain

How does this apply to forensic science and crime investigations?