forensic biology 1/3

serology

the scientific study of serum and other bodily fluids

forensic serology

identification and characterization of body fluids

Physical evidence can be collected from ____ , ______ and ________

crime scenes, individuals and objects/evidence

evidence that can provide the answer when and how something happened, and who was involved

When - victim, suspect confession, medical examiner, crime scene, eyewitnesses, videos

How - Victim, suspect, crime-scene reconstruction, blood spatter, firearm projectiles, eyewitnesses, tire marks, and other physical evidence.

Who - DNA, fingerprints, victim id, suspect confession, firearm comparison, eyewitnesses

two key biological evidence that can answer the question who was involved in a crime?

DNA & fingerprints

laboratory accreditation

the evaluation of a lab’s operation

ASCLD

American Society of Crime Laboratory Directors

ASCLD-LAB

American Society of Crime Laboratory Directors- Laboratory Accreditation Board

FQS

Forensic Quality Services

NFSTC

National Forensic science technology center

CTS

Collaborative Testing Services

CAP

College of American Pathologists

SERI

Serological Research Institute

NIST

National Institute of Standards and Technology

ANAB

ANSI National accreditation Board

ANSI

The American National Standards Institute

private laboratories

1. Bode Technology

2. Orchid Cellmark

3. LabCorp of America

4. Reliagene, New Orleans (bought by Cellmark)

5. Scales laboratory, Brandon, MS

6. Legal Genetics, Ocean Springs MS

7. Ron Smith and Associates, Collinsville, MS

state laboratories

• Jackson, MS (State lab for the state of Mississippi)

• Tallahassee, FL (State lab for the state of Florida)

federal laboratories

• FBI (Federal Bureau of Investigations)

• AFDIL (Armed Forces DNA Identification Laboratory)

• Army lab – USACIL (Georgia) United states Army criminal investigation laboratory)

• ATF (Alcohol, Tobacco and Firearms)

• DEA (Drug enforcement Administration)

• US Postal Service

three manuals required in a serology lab

1. procedures

2. training

3. quality control

proficiency test

an examination administered to case work analysts to check their competency in results or casework analysis

different types of proficiency tests

internal (done in house)

external (done by commercial providers)

known (written)

blind (without knowledge)

agencies that provide proficiency test

1. CTS – Collaborative Testing Services

2. CAP – College of American Pathologists

3. Cellmark

4. SERI – Serological Research Institute

5. RTI International Institute

6. American Proficiency Institute (Hospital labs)

quality assurance

written documentation of how quality is going to be maintained

quality control

documentation after calibration is done- when, who and what

2 types of associative evidence and examples

class characteristic (not unique) - carpet fibers

identification (individualized/unique) - fingerprints

4 essential pieces of information that goes on the evidence envelope

1. Case number

2. Items with description

3. Date

4. Initials (partly on seal, partly on envelope)

Locard’s exchange principle

2 objects come in contact with one another, a transfer of material will occur

3 different types of test to determine a body fluid

1. Presumptive test

2. Confirmatory test

3. Species specificity test

presumptive test definition and example

preliminary test where a positive result indicates the POSSIBLE presence of a particular body fluid

ex. phenolphthalein test —> blood

two sub-types of presumptive test for blood

1. Catalytic color test

2. Chemiluminescence and fluorescence tests

two examples of catalytic color test

Phenolphthalein

Hemastix

Luminol belongs to this type of test

chemiluminescence

true or false: The presumptive tests are much more sensitive than confirmatory tests

true

Describe the so called method of paternity testing in the Hsi Yuan Lu compilation (1250AD)

Blood of parent and child was obtained by cutting their fingers and allowing the blood to drip into a basin of water. If smooth, they were considered related, if clumped it indicated incompatibility and therefore non-relatedness

“Blood stains: Their detection and the Determination of Their Source” was written by who and when

W.D. Sutherland; 1907

Blood grouping was discovered in what year and by who

1901; Karl Landsteiner

Nobel prize was awarded to Landsteiner for his discovery of

blood grouping

phenolphthalein is what kind of indicator

pH

peroxidases

enzymes that catalyze the peroxide-mediated oxidation of organic compounds

generalized peroxidase reaction and each component identified

AH2 + H2O2 -> A + 2 H2O

AH2 = donor (any oxidizable substrate)

H2O2 = hydrogen peroxide

A = colored end product

the process of phenolphthalein reagent preparation in the laboratory; name of chemicals, how it is made, and what happens during the reaction

1. The reaction starts with phenolphthalein powder.

2. Add powder to water to create a milky substance.

3. Make the solution basic by adding NaOH or KOH.

4. The solution should immediately become a dark pink/almost black color.

5. Add Zinc as a reducing agent.

6. Boil the mixture for several hours. As the solution boils, the pink color should gradually disappear.

7. The phenolphthalein is reduced to a colorless, reduced form.

8. The resulting reagent should be colorless, alkaline, and reduced

other name for Phenolphthalein test

Kastle-Meyer color test

what is the oxygen donor in the phenolphthalein test for blood

Hydrogen Peroxide (H2O2)

the active ingredient in the Hemastix test strip

TMB – Tetramethylbenzidine

similarities and differences between chemiluminescence and fluorescence tests

similarities

Both are used when blood cannot be seen with naked eye

Both are oxidation reactions

both are presumptive tests for blood

differences

Chemiluminescence - produces light from a chemical reaction, no additional light/ALS needed, ex: luminol, reaction only lasts ~30 seconds

Fluorescence - occurs when a chemical is exposed to a particular wavelength of light (usually UV), it does require ALS, ex: Fluorescein, fluorescence lasts longer that the other test

Blood group analysis is based on ____ and ____ reaction

antigen and antibody