Untitled Flashcards Set

Lecture 1

Definition of Forensic Science

Science derives its integrity from adherence to strict guidelines that endure the careful and systematic collection, organization, and analysis of information

Forensic scientists use cutting-edge scientific techniques to examine and interpret evidence in connection with civil and criminal proceedings.

Services of Crime Laboratories

Crime investigation:
a.) begin to formulate a question worthy of investigation                            (ex. “What killed the victim?”)

b.)formulate a reasonable explanation to the question

c.) collect and analyze data 

d.) data, findings

e.) arrest, trial by jury, jail

Medical Study:

a.) formulate a question worthy of investigation                                              (ex. “Do processed foods lead to heart disease?”)

b.) formulate a reasonable explanation 

c.) collect and analyze experiment data

d.) publish data/findings

The Scientific Method

a.) purpose/objective

b.) hypothesis

c.) methodology

d.) results

e.) conclusions

Scientific Measurement & Experimental Errors/Reasonable Doubts

a.) Gross errors (human blunders)

b.) Systematic Errors- consistently repeated when a particular equipment/device is used

c.) Random errors- vary unpredictably from one measurement to another

Lecture 2

Crime Scene Investigator (CSI)

-Usually a police officer assigned to a crime scene unit

-Learn from F.S.

a.) How to recognize evidence, collect, preserve, and record it

-May have a science background

-Maintain a Chain of Custody

Forensic Scientist (F.S.) 

-Civilian-scientist

-Furnish training for CSI

-½ of their job is spent in the lab, ½ in court

Crime Lab: 5 Basic Services

1. Biological Science Unit- experts who process and analyze evidence of blood, DNA, bodily fluid, plants, insects, etc.

2. Physical Science Unit- chemistry, physics, geology

3. Firearms Unit- weapons, guns, bullets, etc.

4. Document Examination Unit- handwriting, original vs. forgery

5. Photography Unit- document crime scene, preservation of the scene forever

Toxicology expertise in house (only when funded)

Cyber Technology/IT (only when funded)

Lecture 3

Crime Scene Investigation

Archeological Site/Dig vs. Crime Scene Investigation

Similarities:

Timing- time may be of the essence 

Plan of Attack- systematically searching the site to ensure that nothing is left behind, limit redundancy 

Safety Issues- safety of scenes searchers

Appropriate Personnel- well trained experienced personnel

Controlling the Scene- to minimize contamination and loss of evidence

Documentation- record of  scenes condition and evidence

Difference: Chain of Custody (CSI) 

First Officers Response

1.  Ascertain that the perpetrator is not present

2. Tend to the injured

3. Call for assistance- medical/HQ

4. Secure the scene

Protocol at the Crime Scene

1. Preliminary scene examination by CSI

a.)secure the scene

b.)look for modus operandi (M.O.): pattern/method of operation used by perpetrator to commit the crime

2. Systematic Searches of Crime Scene

a.)spiral search

b.)line search

c.)grid search

d.)zone search

Recording the Scene

1. Sketch- free hand notes

Provide Clues for the Evidence at the Scene

1. Context of the Crime

2. Type of the Crime

3. Type of Scene

Lecture 4

Microscopes

Modern forensic microscopes offer ultra-high magnification levels for looking at small particulates or tool markings. The use of microscopy in criminal science can help ensure the efficacy and accuracy of our justice system. 

Types of Microscopes

• Compound Microscope

Reflected light instruments, with the exception of fluorescence microscopes and comparison microscopes used to study bullets and tool marks, have found limited use in forensic laboratories and are generally confined to the examination of metals that have been prepared by grinding and polishing.

• Comparison Microscope

Specialized features in a comparison forensic microscope may include dual stages and dual optical paths, allowing investigators to simultaneously observe and compare two small items side by side.

• Polarizing Microscope

Polarized light microscopes make use of properties of light and the objects it illuminates to identify and characterize trace evidence found at crime scenes.

• Stereomicroscope

low power microscopes that provide three-dimensional views of specimens visible to the naked eye.

• Microspectrophotometer

measures the light intensity that is transmitted, absorbed, or reflected by a sample at each wavelength of the visible or ultraviolet region of the electromagnetic spectrum.

• Scanning Electron Microscope

enables forensic scientists to visualize trace materials at high magnification and resolution. It facilitates a detailed examination of the surface morphology, texture, and structural features of trace evidence.

Lecture 5

Evidence: anything that tends to prove or disprove something at issue

a.) must be relevant 

b.) must be material- pertains to the particular crime being investigated and not some previous incident

c.) must be probative- actually proves something

Classification of Evidence

1. Physical vs. Non Physical Evidence

2. Real vs. Demonstrative Evidence (created to explain evidence, produced after the crime)

3. Known vs. Unknown Evidence

4. Individual vs. Class Evidence

Databases

1. Integrated Automated Fingerprint Identification System (IAFIS)

2. Combined DNA Index System (CoDIS)

3. National Integrated Ballistics Information Network (NIBIN)

4. International Forensic Automotive Paint Data and Query (PDQ)

Lecture 6

Blood: a solution of various materials in water

Cells= solid portion of blood, 45% of total blood volume 

a.) red blood cells (RBC; erythrocytes)

Transport gases (oxygen and carbon dioxide)
Produced in bone marrow

Lifespan (120 days)

Have no cell nucleus 

b.) white blood cells (WBC; leukocytes)

-immune response

-produced in lymph nodes

-lifespan from 3-20 days dependent on type of WBC

Blood Groups/Types      Antigens (Ag)     Antibodies       Donate Blood to     Receive Blood 

O- universal donor

AB- universal recipient

Lecture 7

Crowners become coroners

Rief of Shire: county becomes sheriff

Coroners: 

-Brought from England to North AMerica

-Elected Official- usually affiliated with a political party

-Term of office: 2-4 years

-May/may not be M.D.

-Duty: to convene inquisition with a jury- investigate suspicious deaths

Medical Examiners (M.E.)

-Brought from France+Scotland to North America in late 1800s 

-Appointed official

-Term of office: continuously until termination/retirement

-Must be M.D. forensic pathologist

-responsible for certifying manner and cause of death

-perform autopsy

Death investigation process

1. Discovery of body

2. Cause of death primary cause (immediate cause of death) and secondary cause (contributing factors of death)

3. Manner of death: set of circumstances that existed at the time the death was caused 

Autopsy: examination of the body

a.) external

b.) internal 

CAUSE OF DEATH, MANNER OF DEATH

Autopsy

Patt

Patterns of Injury/Classification of Violent Deaths

1. Mechanical Cause

2. Chemical cause

3. Electrical Cause

4. Thermal Cause- hyperthermia, hypothermia

(eg. homicide) 

Post mortem interval (PMI)- time of death (helps to establish/refute alibi of suspects)

Early PMI- 1st- 48 hours after death

1. Algor Mortis: tendency of the body to cool after death down one degree every hour after death

2. Effective in estimating PMI if death took place within 12 hours of being discovered

3. Rigor Mortis: degree of stiffening of the body (1.) death muscles and joins relaxed (2.)

2-5 hours later muscles contracted; joints stiffened, rigor mortis began, (3.)after 12-24 hours rigor mortis completed, (4.) within 2-3 days rigor mortis disappears)

4. Livor Mortis- onset is rapid occurs after about 30 mins following death

B.Other Ways of Estimating PMI C. Late PMI

IV. Embalming V. Forensic Anthropology VI. The Human Skeleton

1. Identification of Major Bones B. Functions

2. Identification of Skeletal Remains

3. Is the Specimen Bone?

4. Is the Specimen Human Bone?

Biological Profile: A.) Age of Death

1.)Using Dentition 2. Using Bone Development 3. Using Pubic Bones

Low Velocity Spatter- spatter created by a force travelling at about 5ft/sec or less; produced drops with diameters greater than 3 mm

Medium velocity spatter- a force travelling at about 5-100 ft/sec; drops with diameters between 1-3 mm 

High Velocity spatter- a force travelling over about 100 ft/sec drops with diameter less than 1 mm

1. Impact Spatter- when blood is impacted against a surface

2. Forward spatter- spatter projected outward and away from the source (exit wound)

3. Back spatter- blood projected backward from the source (entrance wound)

4. Cast off spatter- blood expelled from a weapon/object when it moved in the air

5. Arterial Spray Spatter- blood expelled from a wound in an artery

Area of Convergence- point on 2D plane

Area of Origin- point on a 3D plane

1. Locating Blood on Objects

   • Preliminary Tests for Blood- tests used to screen for the presence of blood

   • Confirmatory Tests for Blood- more specific tests used to confirm the bloods presence after preliminary test indicates a positive response

2. Species Determination: immunological tests and DNA analysis

Low Velocity Spatter- spatter created by a force travelling at about 5ft/sec or less; produced drops with diameters greater than 3 mm

Medium velocity spatter- a force travelling at about 5-100 ft/sec; drops with diameters between 1-3 mm 

High Velocity spatter- a force travelling over about 100 ft/sec drops with diameter less than 1 mm

1. Impact Spatter

2. Forward spatter- spatter projected outward and away from the source (exit wound)

3. Back spatter- blood projected backward from the source (entrance wound)

4. Cast off spatter- 

5. Arterial Spray Spatter

Area of Convergence- point on 2D plane

Area of Origin- point on a 3D plane

Lecture 9

1. Fingerprints

a.) friction ridges (raised portions of the outside layer of the skin that form rows that curve and loop across the finger

1. Begin to form when the fetus is around 8 weeks of gestation 

2. By the 17th week our finger patterns are fully formed

b.)Dermal pappillae (layer of cells below the epidermis and top of dermis

c.) Dectyloscopy- the science of comparing friction ridges

d.) Classification of Fingerprints

a.) Latent Fingerprint= invisible print resulted from your cells sweat proteins fats and other materials from the body

b.) Patent fingerprint= visible print

c.)Plastic fingerprint

Type of Ridge characteristics (on lecture slide for fingerprints)

Lecture 10

Reflected Ultraviolet imaging system

Fingerprint dusting

Chemical fingerprinting 

a.) Iodine fuming- fats and lipids found in finger print residues 

b.) Silver Nitrate: AgNO3: AgNO3+ NaCl (sweat)

Ag+ Cl - = AgCl

c.) Ninhydrin- reacts with amino acids present in the fingerprint residues

(Ruhemann’s purple)

d.) Cyanoacrylate (super glue)= amino acids, proteins, fats and lipids

e.) fluorescence- add fluorescent dye (rhodamine-6-G) to cyanoacrylate (dyes fingerprint green, argon light) 

IAFIS- integrated automated fingerprint identification system