BIO 102 Forensic Exam #1

Forensic Science

The application of science to criminal matters/the law

Studies used for Forensics

Biology

Chemistry

Physics

Medical science - cadavers

Behavioral Sciences -

Psychology (PHD) cannot prescribe medication

Psychiatry (MD) can prescribe medication

Math - Statistics, accounting

Toxicology

Odontology (teeth)

Entomology - study of insects

Engineering

Document Examination

Computer/IT

Crime Scene Investigator (CSI)

Usually a police officer

Learn from F.S.

How to recognize evidence at crime scene

Protect it from contamination

Collect it properly

Thoroughly document its location + condition

Maintain chain of custody

May have science background

Forensic Scientist (FS)

Civilian with science background/training (do not carry a badge)

Who train C.S.I.

½ of their job → performed in lab/analysis of evidence

½ is testifying in court → what they found/explain to judge + jurors how to understand

Basic Services of Crime Laboratories

Physical science unit → chem, physics, geology

Biological science unit → bio. Blood, DNA, hair, etc.

Firearms unit → weapons, guns, bullets

Document examination unit → handwriting analysis, forgery

Photography unit →

Extra units:

6. Toxicology

7. Fingerprint

8. IT

Scientific Method

The essence of the evidence → must undergo scientific inquiry (Scientific Method)

Science derives its integrity form adherence to strict guidelines that insure the careful and systemic collection, organization, and analysis of information

Crime Investigation

objective/purpose - a question worth investigating: who killed the wife?

hypothesis - guess: husband?

methodology - test hypothesis: gather evidence

results - what actually happened

conclusion - arrest/incriminate/resolve

Medical/Scientific Research

objective/purpose

hypothesis

methodology

results

conclusion

Errors

Gross errors → human "blunders" ; less than careful

Systemic error → consistently repeated each time a particular equipment is used

Random errors → by chance

Crime SCENE Investigation

Timing → time may be of the essence

Plan of attack → for systematically searching the site to ensure nothing is left behind

Avoid redundancy → accuracy + efficiency

Safety issues → safety of scene searchers

Appropriate personnel → qualified, trained personnel to conduct the search

Controlling the scene → to minimize contamination + loss of evidence

Documentation → record of scene's condition + evidence

1st Officers Response

1. Ascertain whether perpetrator is present - 2. remove the "threat"

3. Tend to the injured

4. Call for assistance

5. Secure the crime scene

Crime Scene Protocol

Preliminary Scene Examination

- Further secure scene

- Look for modus operandi (M.O.)

- Pattern/method of operation that a criminal repeatedly uses during an illegal act

Search Methods

Line search → Searching the room/area line by line, combing the area back and forth until they finish the room

Spiral search → Spiraling the room/starting with the perimeter slowly going further into the room until they reach the middle

Zone search → for BIG areas/rooms. Divide room into quadrants and designate certain groups per quadrant.

Grid search → Line search x2. Do a line search, then do it again from another side so it looks you weaved

The Microscope

Optical instrument that uses lenses to magnify and resolve details of an object

Reasons for its popularity in crime lab

- Sample preparation is minimal

- Microscopes can be used for identification

- Microscopy - nondestructive to the evidence; especially crucial when the quantity of evidence is minimal

- Versatile

- Magnification power

- Compare 2 objects side-by-side

- Add high resolution cameras for photographs

- Combine the microscope with other analytical instruments → spectrophotometer

Compound Microscope

- max magnification power of 450x of the object

- Image is inverted

Comparison Microscope

- Two microscopes pushed together

- Allows to have side-by-side comparison of objects

- Often used for analyzing bullets

Polarizing Microscope

- Examine minerals + metals present in soil

- Polarize light → ideal for crystals (found in minerals)

Stereomicroscope

- Space between stage + objective lens is big → allows to look at larger object

- Image is upright

- Easier to manipulate

Microspectrophotometer

- Linking of a microscope to a spectrophotometer

- Infrared absorption spectrum

Scanning Electron Microscope

- The lamborghini of microscopes" - Pamela Yang

- Image is formed by aiming a beam of electrons onto specimen → measures the electron emission

- High magnification (10x to 100,000x)

- Resolution + great depth focus

Evidence

Anything that tends to prove or disprove something

- Must be relevant

- Must be material → pertain to the particular crime being investigated + not some previous

- Must be probative → actually prove something

Physical vs. non physical evidence

Physical

- objects/things "touch + feel"

Nonphysical

- verbal testimony

- First hand memory of eyewitness

- Statements of the arresting officer

- Statements made during interrogation

- Feelings, + emotions about someone

Real vs. demonstrative evidence

Real

- Generated by criminal activity

- Found at crime scene or elsewhere + pertains to the crime

Demonstrative

- Created to help explain or clarify real evidence

- Produced after the crime + not by the crime

- May be performed to illustrate the value of the evidence

Known vs. unknown evidence

Known

- Objects whose source or ownership is known at the time its collected at crime scene or elsewhere

Individual vs. class evidence

Individual

- Arises from only one source

Class evidence

- Arises from several sources; features shared by all members of a group

Forensic Databases

- IAFIS

- CODIS

- NIBIN

- PDQ

IAFIS

Integrated Automated Fingerprint Identification System

Maintained by the FBI

CODIS

Combined DNA Index System

- Enables the federal states and local law enforcements/crime labs to electronically exchange and compare DNA profile

- Maintained by the FBI

NIBIN

National Integrated Ballistics Information Network

- Maintained by Bureau of Alcohol, Tobacco, Firearms, and Explosives

- Firearms + weapons

PDQ

International Forensic Automotive Paint Data Query

- Maintained by Forensics Laboratory Services of the Royal Canadian Mounted Police

Blood

a solution of various materials in water

1. plasma

2. cells

Plasma

liquid portion of blood; 55% of total blood volume

- 90% water

- 10% substances dissolved in here: carbohydrates, fats, proteins, glucose, antibodies, electrolytes - salts + minerals, hormones

Cells

solid portion of blood; 45% of total blood volume

1. red blood cells

2. white blood cells

3. platelets

Red Blood Cells

RBC; erythrocytes

- Transport gases (O2 + CO2)

- Do NOT have a nucleus → do NOT have nuclear DNA

- Produced in bone marrow

- Last 120 days

White Blood Cells

WBC; leukocytes

- Fighting infections; immune response

- Have a cell nucleus → have nuclear DNA

- Many types of WBC

- Produced in lymph nodes

- Lifespan 3-20 days

Platelets

thrombocytes

- Blood clotting mechanism

- Irregularly shaped

- Lifespan 5-9 days

RBC - antigens

a type of protein

Human Hemoglobin

"heme" units

Why a blood type it + or - (blood antigen)

+ → presence of Rh factor

- → absence of Rh factor

Preliminary Tests

Luminol - reagent

- H2O2/heme(catalyst)

- No thickening agent added

Fluorescein - reagent

- H2O2/heme

- Has thickening agent added

Confirmatory Tests

Teichmann & Takayama

- Crystalizing (reagent) + blood (heme) → formation of shaped crystals

- If test is positive, this tells you this is blood, BUT animal or human?

- Immunoprecipitation typing - species determination (animal or human)

Geometry of Blood Stains

Surface texture →

- Hard/non porous surface (ex. Glass, smooth tiles): If blood drops on this... there is LESS splatter

- Rough surface (ex. Concrete floor, wood): Irregularly shaped stains with serrated edges

Shape of blood droplet

- Direction from which it came (direction of travel)

- Angle of impact → angle relative to the surface it strikes

Bloodstain Spatter Patterns

1. Impact spatter pattern

2. Forward spatter pattern

3. Back spatter

4. Cast off spatter

5. Arterial spatter

Impact Spatter Pattern

occurs when blood impacts a surface

Low velocity spatter → pattern created by a force traveling at 5 ft/sec or less + producing drops with diameters greater than 3mm

Medium velocity spatter → 5-100 ft/sec; diameters between 1-3mm

High velocity spatter → over 100 ft/sec: diameter less than 1mm

Forward Spatter

spatter projected outward and away from source (exit wound)

Back Spatter

blood projected backward from source (entrance wound)

Cast off Spatter

ex. Hitting a victim repeatedly with bat, the blood on the bat will fling off after each hit, on a nearby surface; blood "casting off" murder weapon

Arterial Spatter

ex. Spitting up/coughing up blood

Origin of Blood

Area of convergence → point on 2-D plane from which blood drops originated

Area of origin → are in 3-D space from which blood is found

Coroner

- Brought from England to N. America in 1600s

- Elected officials → often as member of a political party

- Term of office: 2-4 years

- May or may not be M.D.

- Duty → convene an inquisition with a jury to investigate the death of a person

Medical Examiner (M.E.)

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

- Appointed official

- Term of office: continuous

- Must be M.D. + board certified (pathologist , forensic pathologist)

- Duty → responsible for certifying manner + cause of death

Causes of Death

1st. Cause → immediate death

2nd. Cause → contributing causes of death

Manner of Death

1. Homicide → murdered; premeditated

2. Natural →

3. Accidental →

4. Suicide

5. Undetermined

Autopsy

examination of the dead body

- External autopsy

- Internal autopsy

Pattern of Injury + Classification of Violent Death (i.e. homicide)

- Mechanical causes → forced trauma

- Chemical causes → poisons, substances, drugs

- Electrical causes → high electrical voltage

- Thermal causes → burns (hyperthermia) or extreme cold (hypothermia)

Early P.M.I

1st 48 hours after death

1. Algor Mortis

2. Rigor Mortis

3. Livor Mortis

Algor Mortis

= tendency of a body to cool after death

- General rule: your body cools down 1 degree every hour after death (with appropriate clothing)

- Ambient temperature is crucial

- Used as a method to estimate P.M.I within 12 hours of body being discovered

Rigor Mortis

degree of stiffening of dead body

Livor Mortis

= pooling of blood at lowest part of body

- Onset is rapid - 30 min after death

- Permanent

- (this can tell people if the body has been moved before)

Other methods of estimating P.M.I

1. Potassium level in the eye (eye will be all white)

- Linear increase from 12-100 hours after death

2. Stomach content

Late P.M.I

when you see decomposition of body + discover insects

Embalming

putting a chemical in a dead body to preserve the tissue for an open casket funeral/forensics do not like doing this until all the evidence + information has been collected

Anthropology + Forensic Anthropology

1. study of humans, including their cultures + biology

2. involves application of osteology (study of bones) + skeletal identification to matters involving the law

Bones to know

Cranium - skull

Mandible - jaw bone

Clavicle - collar bone

Sternum - protected by rib cage

Vertebra - spinal column

Humerus - bicep bone

Radius - bone aligned with thumb

Ulna - aligned with pinky

Pelvis - hip bone

Femur - thigh bone

Tibia - thick shin area

Fibula - thinner calf bone

What is a Bone?

- living, functioning entities

- Grow + change overtime, as they can alter + repair themselves as needed

- Contain marrow

- Site of growth

Functions:

- Support the body

- Protect delicate organs

What type of bone?

Is the specimen bone?

- Haversian canals

Is the specimen human bone?

- Plexiform bone - animal

- Absence of plexiform bone = human!

Biological Profile

1. Age of Death

2. Gender

Age of Death

Dentition (teeth)

- Incisors - 9 month age

- Permanent - 6 years age

- Wisdom - between 17-21 years age

Bone development

- Young adults - surface is rough

- By age 35 - surface becomes smoother + develops a rim

- After age 35 - surface degenerate + erodes

Finger Prints

- Friction ridges = raised portions of the outside layer of the skin that form rows that curve + loop across the finger

- Dactyloscopy = science of comparing fingerprint

- Dermal papillae - layer of cells below epidermis + top of dermis

Classification of Fingerprints

- Latent fingerprint = invisible prints resulted from your cells, sweat, proteins, fats, and other materials from body

- Patent fingerprints = prints that are readily visible in paint or blood

- Plastic fingerprint = prints that are formed in a soft material aka an impression (i.e. puddy, clay, etc)

Anatomy of fingerprints

1. Types of ridges

2. Patterns of prints

Types of ridges

Bifurcation

Ending ridges

Dot

Short ridge

Enclosure

Trifurcation

Patterns of prints

Plain arch

Tented arch

Radial loop left hand

Ulnar loop left hand

Plain whorl

Central pocket loop whorl

Double loop whorl

Accidental whorl

How to identify prints

1. Reflected UV imaging system

2. Iodine fuming

- residuals (fats, lipids) in fingerprint

- Reddish brown

3. Silver nitrate

- salt found in sweat

- Ag+ Cl → AgCl

4. Ninhydrin → great for porous surfaces - ruhemanns purple

- Reacts with amino acids

5. Cyanoacrylate - "superglue"

- Reacts with amino acids, fats, proteins

- White precipitate

- Moisture speeds up process

6. Fluorescent → cyanoacrylate + fluorescent dye + light