lecture 1

Question 1

criminalistics is an applied science

Answer 1

uses the concepts, techniques and theories learned in the sciences and applies them to the detection of crime i.e. forensics

Question 2

forensic biology applied science

Answer 2

applies the principles of biology to the detection, identification, and identity of biological evidence as it pertains to the law

Question 3

direction of forensic biology

Answer 3

automation
batch sampling
statistics

Question 4

course objectives

Answer 4

types of bio evidence (blood, saliva)
screening presumptive tests
confirmatory tests
evidence sampling
extraction
quantitation with par measure after each cycle and extrapolate
amplification and STR typing
STATS &. CODIS
other types of DNA

Question 5

bio evidence what to keep in mind

Answer 5

questions of evidence
limitations

Question 6

questions of evidence

Answer 6

what is it - identification of bio fluid - conventional serology
who is it from- indicidualization or identity - DNA analysis and comparison
under what circumstances was it deposited - bloodstain pattern analysis - consensual partner vs. sexual assault
can we determine when it was deposited - time of deposition - post-coital interval

Question 7

know the limitation of the tests you are using

Answer 7

specificity and stability of markers
specificity of assay
sensitivity of assay

Question 8

an example of what a forensic biology analyst dies

Answer 8

screens for bio flued
takes samples of stains for DNA analysis
extracts DNA from samples
quants samples
amplify and types samples
interprets dna profiles into codes
produces a stat on all matches or inclusions
writes as report
testifies in court

Question 9

heme detector

Answer 9

cross reacts with menstrual period blood

Question 10

ideal characteristics of a forensic body fluid marker assay

Answer 10

body fluid marker:
single marker unique to human body fluid - species determination with body fluid identification
expressed in everyone at the same level independent of sex and age
stable outside of Boyd and under diff environ conditions
slow and predictable decay rate independent of enviro
assay for marker:
specific
sensitive
reproducible and reliable
robust
easy to use
inexpensive
portable for field use

Question 11

3 levels of quality for a crime lab

Answer 11

quality control - something you do within the laboratory
quality assurance
accredidation

Question 12

quality control

Answer 12

positive and negative controls when testing unknowns
technical and administrative review of case documentation

Question 13

quality assurance

Answer 13

instrumentation is often validated for case work
all newly made reagents must show that they work prior to being used in case work
agreeing to hold to the standards that we say we are following
fbi guidelines for dna

Question 14

accredidation

Answer 14

when an outside body reviews all policy and procedure manuals in the lab and case work to ensure policy meets or exceeds expectation of the agency or federal gov and that lab is following its own policy and procedures and that instrumentation is being used and reported out appropriately

Question 15

case management
packing of biological evidence

Answer 15

evidence from diff sources should be packaged separately
be careful when you need to fold evidence, wet blood can transfer
if wet evidence must be packaged, document prior to packaging
fold in clean butcher paper and dry when at the lab
package potential bio evidence in paper bag or breathable tube, not plastic
trace evidence like hairs should be collected in a paper using a druggist fold
all evidence should be labeled with case number date and initials
sealing on evidence use evidence tape tamper evident with initials and date
do not cut and evidence seal if possible, make opening in new area of packaging

Question 16

analysis of bio evidence

Answer 16

many questions are case or context specific
to anser wuestions we need to know the circumstances of the case
blood covered knife left next to a stabbing victim, would the presence and identity of the blood be more important or the fingerprint left in blood
beware of contextual bias

Question 17

contextual bias

Answer 17

when the decision of a person is influenced by extraneous often ambiguous info that is not needed to draw the conclusion
a fingerprint examiner who receives a file containing prints and a case summary suggesting the suspect is the actual perpetrator may be more likely to find that the prints match than an analyst who receives no case info

Question 18

recognition of bio evidence

Answer 18

corpus delicti - demonstrates that a crime has occured
locards principle
victim to perpetrator linkage
vitime to scene linkage
perpetrator to scene linkage
modus operandi, case to case linkage

Question 19

comprehensive approach to the analysis of bio evidence is necessary

Answer 19

always consider that there may be multiple types of physical evidence present on an item, trace and fingerprint, etc
some items pressure multiple processing
know the requirements of other forms of analysis

Question 20

sampling and sample selection

Answer 20

representative/ uniform
methods
scraping or picking (put in druggists fold)
cutting
tape lift
swabbing ( concentrate sank on as small as an area as possible, air dry, starage
M-vac
environmental/ substrate samples
take to evaluate background
field kit controls

Question 21

collection devices

Answer 21

bode secure swab
m vac

Question 22

sample collection and recovery

Answer 22

consider a condom
make observations
is the condom inside out right side out
anticipate potential issues
one or two samples
consensual partners?

Question 23

sample collection and recovery

Answer 23

blood stain
blood is water soluble
how big is the stain
how many stains were there
how many bleeders
take representative samples
swab vs cutting vs scraping
semen staind
semen is also water soluble but sperm can be sticky
locating stains may be difficult
how many people are you looking for?
could there be contamination
a consensual partner?

Question 24

consider sample requirements

Answer 24

policy and procedure of agency
retention of one-half of the sample
reanalysis (defense split)
do not assume that your substrate is uniform ( swab/cutting)
testing
determine the appropriate tests
consider the type of sample
what is needed for each test
stain extraction procedure
water vs water detergent
extraction buffer for sandwich immuniassays may not be compatible with other tests
served PSA test
low ph values can lead to false positives
search for universal buffer PBS?

Question 25

workstation environment

Answer 25

clean Bech top before and after each sample examined or case
70 % ethanol 10% bleach or other cleaning solution
other casework must be secured or removed
use universal precautions
all subjects and bio samoekes are assumed to be infectious agents for blood born pathogens
potential for HBV (hep B) transmission in the workplace is greater than HIV transmission
blood is the single most important source of HIV and HBV in the workplave
document and let your supervisor know if you have an exposure
PPE personal protective equipment
lab coat disposable apron
sleeve protectors
gloves change between items of cases or as needed
mask and or face shield
eye protection

Question 26

lab examination documentation

Answer 26

note taking
case number, analysis’s initials and date on all pages
chain of custody
number pages: __ of (total)
single line cross out clerical mistakes, initial and date (no obliterations)
standardized worksheets and pre made diagrams
sketches, digital images and photographs are all part of documenting

Question 27

workstation and documentation

Answer 27

always describe packaging seal and initials
avoid breaking existing seals close with new seal and you date and intiials
open evidence packaging carefully over a clean covering
check f0r material adhering to packaging or if anything falls out or off of items (hairs)
describe evidence as received
what is it what does it look like smell stains color size shape how Many anything you want to add
describe condition of evidence
items in contact with one anoteher
dry or wet drying cabinet

Question 28

avoid contamination

Answer 28

have one case opened at a time
have one item of evidence opened at a time as necessary
have only one tube open at a time
use a decayer tool
be aware of aerosols (DNA), from opening tube
clean instruments single use disposables
replace pipette tips between samples
use aliquots of stock solution
sequence analysis of samples and controls
unique sample identification numbers
durable labels and ink