forensic biology

for quiz 1 and test 1

serology

scientific study of serum and other bodily fluids

serology blood test

performed to detect & measure antibodies from bacteria/virus exposure

forensic serology

identification & characterization of body fluids

forensic science

the application of science to the criminal laws that are enforced by police agencies in the justice system

what forensic science does

• unique role in criminal justice system & society

• supplies objective & accurate information that reflects events

• evidence based results & conclusions

• used to prove innocence or guilt

physical evidence

can aid investigation by answering

• whether a crime was committed… if yes…

  • when?

  • how?

  • who?

the laboratory

• an integral part of forensic science

• more possibilities this decade/century

• advanced technology provides more tools to study evidence

laboratory responsibilities

• not just analyzing physical evidence

• recognition of the invisible items

• proper collection

• preservation and storage

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

state laboratories

• Jackson, MS

• Tallahassee, FL

local laboratories

city and county

private laboratories

1. Bode Technology

2. Orchid Cellemark

3. Labcorp of America

4. Reliagene, New Orleans

5. Scales laboratory, Brandon MS

6. Legal Genetics, Ocean Springs MS

7. Ron Smith and Associates, Collinsville MS

government laboratories (service)

primary focus on criminal cases & offender data basing

private laboratories (money)

focus on criminal cases, paternity cases, offender data basing for CODIS etc.

laboratory staffing

multiple disciplines in 1 laboratory

• members mostly trained in 1 discipline

• may have training in more than 1 discipline

laboratory disciplines

• biology

• chemistry

• firearms

• latent prints

• document examination

• crime scene processing

laboratory accreditation

formal evaluation showing that they meet specific quality, competence, and reliability standards

laboratory accreditation agencies

• ASCLD-LAB (American Society of Crime Laboratory Directors Laboratory Accreditation Board)

• FQS (Forensic Quality Services) now part of ANAB

• NFSTC - National Forensic science technology center (Evaluates, guides and audits lab-no certification)

accreditation bodies

• ANAB – ANSI National accreditation Board

• ANSI – The American National Standards Institute

• ASQ – American Society for Quality

• FQS – Forensic Quality Services

• ASCLD- American Society of Crime Laboratory Directors

• ASCLD-LAB - American Society of Crime Laboratory Directors- Laboratory Accreditation Board

accreditation parts

review

• lab operations

• security

• personnel

• policies

• procedures

quality assurance

written documentation of how quality will be maintained

quality control

documentation after calibration is complete:

• when wast it done

• who did it

• what is the result

quality assurance addresses

• overall policies

• administrative policies

• personnel qualifications

• job description

• case acceptance policies

quality assurance addresses

• chemical preparation log

• chemicals and kits validation

• annual instrument check with SRM

• acceptable and unacceptable values and reagents

color development tests for detecting blood

• Phenolphthalein test

• Benzidine tests

• Hemastix test strips (TMB) 

• LMG (Leucomalekite green) test 

• O-Tolidine test

• TMB (Tetramethyl Benzidine) test

• DAB (Diamino Benzidine)

phenolphthalein test

relies on peroxidase like civility of blood to react with chemical & change color

peroxidases

enzymes that catalyze the peroxide mediated oxidation of organic compounds

hemoglobin

if it shoes the peroxide mediated oxidation it has peroxidase

peroxidase reaction

AH2 + H2O2 —> A + 2H2O

AH2 - donor (oxidizable substrate)

H2O2 - hydrogen peroxide

A - colored end product

phenolphthalein color code

oxidized - pink (when exposed to H2O2)

reduced - colorless

phenolphthalein test —> Kastle-Meyer color test

phenolphthalein + H2O2 + blood —> pink —> blood present

phenolphthalein test properties

• principle (blood = pink)

• aim of test (detect blood)

• materials required

• results (color change)

• conclusion

hemastix test

• blood in urine

• forensics screening tool

• same idea as phenolphthalein test

• TMB (tetramethylbenzidine) is active reagent

• diisopropylbenzene dihydroperoxide + buffers

hemastix color code

yellow - no blood

green/blue green - blood

chemiluminescence test

• light emitted due to oxidation

• heme group accelerates oxidation of luminol —>blue-white / yellow-green

• reaction lasts ~30 seconds

fluorescence test

occurs when substance is exposed to a particular wavelength of light (usually UV)

fluorescein

• same principle as phenolphthalein

• reduced to fluorescin with zinc

• heme group accelerates oxidation by H2O2 of fluorescin to fluorescein

past blood testing methods

• ABO blood group typing

• enzyme markers

• secretor status

ABO blood typing

• used widely in past for ID of blood for typing

• not presumptive or confirmatory

• characterizing blood to see if it has the same type as sample

Karl Landsteiner 1901

• most significant discovery in medicine

• blood grouping

• called groups A B & C

Jansky (1907)

• tested cells from 99 people and sera of 30 people

• involved 3100 agglutination tests

• recognized existence of 4 isoagglutination groups

• no mention of Landsteiners work

• 4 groups —> I II III IV

Moss (1910)

• examined blood from 100 people

• 4 isoagglutination groups

• groups —> IV III II I

• reverse of Jansky system

Von Dungern and Hirszfeld (1910)

• experiments on isoagglutination groups

• 4 groups

• presence or absence of 2, A & B

• agglutinins designated as α & β

blood composition

• plasma/serum (~55%)

• red blood cells

• white blood cells

• blood platelets

blood composition amounts

• red ~ 5,000,000 mm3