Forensic Science Final

Serology

identification using body fluids

Medical Serology

Applications: Used to do disease detections

Collection: Collecting a certain number of tubes

Availability: people can get drawn, if more tests needed can just redraw

Have control over conditions, quality, and quantity.

Forensic Serology

Application:Used to make comparisons

Collection: Have no control over the environmental conditions

Availability:Whats at the scene is all we have.

How much of a sample needs to be retained for defense

At least a quarter of the sample.

The 3 most commonly encountered BF

blood, semen, saliva

Which body fluids can be confirmed and identified 100%

blood and semen

For saliva what can we say

presence of saliva indicated

What parts of blood are forensically significant

Red blood cells, white blood cells, serum

what do we do with the RBC

contains heme which is what we detect in order to identify

what do we used WBC for

used for DNA tests

Serum

contains clotting factors and antibodies used for confirmation

identification of blood (screening stage)

Place reagents onto the stain and if RBC are present, reacts with the heme of RBC which creates a color.

Phenylphalene test (aka Kastle- Meyer or KM) which gives a pink color

Leuko-malachite green gives a blue/ green color

What does the screening part do

Helps narrow down what could be stain. If it’s negative, it’s done. If its positive, move to confirmation step.

Can you tell what a stain is just by looking at it

nope

Confirmation of Blood

Ochierlony- looks for the presence of antibody/ antigen in an antihuman serum

Hematrace ABA card

Ochterlony

Petri dish with agarose gel, holes made in the gel and in the center. In the center all add anti-human serum and in the surrounding wells place antigen extract and in solution are the antibodies. Watch for the antigen to come out of the well and meet the antibody to produce a precipitant band.

Semen

contains the sperm

Seminal Fluid

fluid with no sperm

Forensically significant components of semen

Sperm

Acid Phosphatase

P30

Acid Phosphatase

enzyme in semen/ seminal fluid, yeast, breast milk, vaginal secretion. This is a screening.

P30

protein specific to the male prostate. confirmatory.

Identification of semen

Acid Phosphatase Test.

If negative, done

If positive, move on to confirm.

Sperm

Use compound microscope to identify human, confirmatory.

What can cause low sperm count

Stress, high fever, congenital condition, drugs.

Confirmation of Sperm

1. ID sperm

2. P30

Process of ID Sperm

Centrifuge to pellet, put on slide, Christmas tree stain

Christmas Tree Strain

Head-red

Midpiece- blue/green

Tail- Green

process for identification of P30

card w/ antibody

What would “Presence of Semen detected” mean happened

acid phosphatase and ID of sperm

What would “Presence of Seminal Fluid was detected” mean occurred

Positive acid phosphatase and P30, but no sperm were identified.

Forensically significant components of saliva

amylase (enzyme)

Screening for Saliva

Phadebus test- tablet that has starch w/ dye and if it indicates amylase it will break down the tablet and produce a blue colored solution.

Conformation of Saliva

Cannot be done.

false positives with kastle Meyer reagent

horseradish peroxidase and rust.

Roles of a forensic biologist

screening evidence, looking for BF, use black light to find semen, utilize compound microscope, removal of adhering trace evidence.

Flow of Crimes

1. Crimes against People

2. Crimes against property

3. Motor Vehicle accidents

Priorities

1. Rush Case (Court Date Pending)

2. Need to get enough evidence to build a warrant/case on someone

3. Homicide

4. SA w/ suspect

5. SA w/o suspect

6. Burglaries

Case load CLS vs FS

CLS- run multiple samples at a time

FS-1 case at a time → backlog builds.

Handling biological specimens

Wear protective clothing and equipment. Air dry before placing into cardboard bags.

substrate controls

area adjacent to the sample without body fluid.

ruler

gives potential scale

tapelift

place to pick up small trace evidence

quality control

use to test if reagents are working

examples of body substances

dandruff, mucous, skin cells.

To find the location of Semen

visual exam

polilight(helps identify areas to be tested)

mapping (done on a larger item, spray with water, lay down a paper and press an item into it, then spray acid phosphatase, if it turns purple thats where its located.)

for identification of P30

use lateral flow assay with a prostate specific antigen

what is spermatozoa

cells of reproduction produced by males

seminal fluid

fluid produced during ejaculation containing sperm

Why is DNA better than ABO testing

There’s only 4 blood types, not very discriminating.

secretor

releases the ABO type antigens in other BF

Luminol

used to locate cleaned up blood through emission of light

PCR

used to look at 13 areas of DNA and makes copies of the DNA

can see melogenin which is the gender marking

Short Tandom Repeats

area on chromosome where there are variations

If the blood is on what color dyes, can we not do PCR

Purple or black dyes.

Tanic Acid

in leather, prevents us from doing PCR

Humic Acid

in soil, prevents us from doing PCR

Quanti-blot

tells us the amount of DNA in a sample

import because too much DNA is bad.

CODIS- Combined DNA Index System

1. Forensic Unknowns

2. Convicted Felons

3. Unidentified/missing people

Unknown samples can get searched with the convicted felons and can link multiple cases together.

SANE

Sexual Assault Nurse Examiner- individual that collects the kit from you.

Steps of the Kit

Starts with questionnaire

1) Buccal Specimen

2)Vaginal, Anal, Oral Swab and Smears

3)Dried Secretions & Bite marks

4) Fingernail scrapings

5) Underwear

6) Debris collection

7) Pubic Hair Combing

8)Known pubic hair

9)Known Head hair

Buccal Specimen

Cerated swab run along inside of the cheek. Gets air dried and placed into paper. This is a known sample of the victim.

Dried secretions and bite marks

use sterile swab, add water, swab spots and dry. add to paper. looking for evidence of perp.

Vaginal, anal, oral smear and swabs

cardboard containers with glass slides. touch swab to glass. allow to dry. swab placed in sterile cardboard. looking for evidence of the perp.

fingernail scrapings

run under nails, looking for evidence of the perp.

Debris collection

hair, fibers, soils, leaf. use a spatula to brush evidence leading to perp off of clothes.

pubic hair combing

use comb to lightly brush through public hair

looking for evidence of perp.

over the counter drug

walk in and buy

prescription

comes from a doctor’s script

Why are paper prescriptions untrustworthy

The pad is easily stolen and if it’s handwritten it’s very hard to authenticate.

Dr shopping

get a script from 1 dr, misuse it, go to another and get another script.

Online scripts help prevent this because they all us to track the prescriptions in real time.

drugs of abuse

substances—including illegal drugs, alcohol, tobacco, and misused prescription medications—that are taken to alter mood, perception, or consciousness, often creating pleasurable effects on the brain. ex-ectecsy → Narcotics

designer drugs

chemically similar to a drug that is highly abused

motting

part of the illegal drug processing procedures. Substances added without quality control. Shows as speckling.

Logo

used to sell products. try and appeal to various groups.

drug diversion

take legal drug but use it illegally

clandestine lab

secret lab where drugs are being manufactured illegally. could be in an abandoned building or barn. can be stationary or mobile.

ion scan

instrument that looks for traces of drugs.

drug concealment

ways that drugs are illegally smuggled into the country

Field Test

This is a screening test. take small portions of a drug. at a scene, place into small plastic bag has ampuele containing reagents, crush it and receive basic information about what kind of drug it is.

Roles of Chemist

analyze evidence, support law enforcement, conduct research and develop new methods, develop intelligence data to determine trends of production, provide expert testimony.

Do all chemistry substances go to the lab

yes. not all biological substances go.

types of chemistry evidence

powders, liwuids, tablets, capsules, injection vials, blotter paper.

Suspected substances

Narcotics

Hallocinogens

Stimulents

Depressants

Cannabis

Steroids

Pharmaceuticlas

Marquis reagents

detects heroin, morphine, MDMA, methamtheamines

salt reagents

detects cocaine

duquenois levine reagents

detects marijuana, hashish, thc

Are drugs pure

No, most are not. Typically dillunents get added to it which brings bulk to the packaging. This means more $$