Body Fluids Flashcards
what is forensic biology/serology?
study of cells and serums
how are body fluids important to Crime Scene Investigations?
DNA
Forensic Toxicology
what is DNA?
personal blueprint carries a genetic code that individualizes each person, except identical twins
what is toxicology?
presence of drugs/alcohol in body fluids
where are these body fluid samples collected?
samples taken at DUI centers/hospitals and sent to lab
samples taken at autopsy and sent to lab directly, not to CSI
types of samples sent to lab directly
vitreous humor - the heartiest type of body fluid that can be found
blood-heart
urine
cerebral-spinal fluid
what equipment is used to collect samples?
use gas chromatography-mass spectrometry
GCMS
DNA types
DNA (nuclear DNA)
mtDNA (mitochondrial DNA)
where is DNA found?
found within the nucleus of cells; therefore any fluids/tissues that have cells with nuclei will have DNA information
who is DNA inherited from?
half from mom and half from dad
where is mtDNA found?
found in the mitochondria in nucleated cells and on-nucleated cells (hair, fingernails)
who is mtDNA inherited from?
maternally inherited
may be found in degraded samples, skeletal remains
The Northern Virginia Forensic Laboratory does not perform ? why?
mtDNA analysis on routine cases
More expensive and extensive to test
Goes to FBI Lab
What body fluids have DNA?
Semen / Seminal Fluid
Vaginal Fluid
Saliva
Perspiration
Urine
Tears
Body/fetal tissues
Bones
Hair
Saliva, perspiration, urine, tears, etc. – not found in liquid itself, found in ?
epithelial cells
where do you look for DNA?
Hats, caps, Masks, Gloves, Socks, Shoes, Toothbrush, Weapons, Clothing, Telephones, Toilet bowl, Sinks, Fingernail scrapings, Envelopes
Think creatively!!
what is touch DNA?
A deposit of epithelial cells from “touching” an object to attempt to obtain a DNA profile
reminders when collecting DNA?
cross-contamination: not always a good sample bc it can be mixed from other contributors (ex: door knob)
PPE: remember to wear gloves and do not breathe onto evidence
what does CODIS stand for?
Combined DNA Index System
what does CODIS contain?
FBI database containing DNA profiles of convicted felons
two types of indexes from CODIS
Forensic Index
Offender Index
what is Forensic Index?
profiles from crime scene evidence
What is Offender Index?
profiles of convicted sex offenses and other violent crimes
are all convicted offenders entered into the database?
No, every state has a different system for uploading these swabs into the system. Depends on state and crime. In state of VA, any felony crime will be uploaded to system and crime will be compared to it
what 3 questions do we ask about blood?
- is it blood?
- is it human?
- Who’s is it?
what is blood consisted of?
blood consists of plasma and cells (red blood cell, white blood cell, and platelets)
what is the function of blood?
carries oxygen to cells via hemoglobin
2 types of tests for blood
presumptive test
confirmatory test
what is a presumptive test?
field test kits, sample of suspected blood is swabbed and tested with chemical
what is used in the presumptive test?
MacPhails reagent
Phenolphthalein- (Kastle-Meyer Reagent)
Leucomalachite green
Orthotolidine
Hematrace- human blood
when shouldn’t you do a presumptive test?
if you have a small sample
where is the confirmatory test done?
done at lab
what is the hematrace test?
will come back and say if it is human blood or not; it will say it is human blood if it is ferret blood
UV/LS doesn’t ? is absorbs (darkens)
fluoresce
types of chemicals used for locating blood
lumimol
fluorscein
blue star
what is luminol?
chemiluminescent compound, extreme sensitivity, need complete darkness, can not overspray, false positives, need PPE, reacts with bleach
what is fluorscein?
needs ALS, does not react to bleach, need PPE
what is blue star?
has a stronger and longer-lasting luminescence that does not require total darkness to be visible, does not alter DNA, works well on fresh, old, diluted, or altered stains
what is seminal fluid composed of?
95% fluid, 5% spermatozoa, 200 million sperm
characteristics of seminal fluid
fluoresces under UV/ALS light
may be detected in victim body orifices for days; rape
type of presumptive test
acid phosphatase test
what does an acid phosphatase test do?
sample stain on swab or filter paper, turns blue/purple
type of confirmatory test
prostate-specific antigen (PSA)
What is prostate-specific antigen?
confirmatory test for semen
other body fluids
saliva
urine
vaginal secretions
where to look for saliva? urine? vaginal secretions?
Saliva: pillow, sink, sidewalk
Urine: does not contain DNA, the epithelial cells do
Vaginal: common and uncommon places look inside the victim’s
parts of urine
Diluted _cell__ concentrations
Large amount of __bacteria__
types of DNA samples from suspects
Blood Samples- need nurse/doctor, purple-top tubes (EDTA), need to be refrigerated
Buccal_ Swab Samples
>Two saturated buccal swabs
>Pre-packaged kits available from the DFS Laboratory
Hair Samples
Clothing collection
taken under ? or a ?
consent, search warrant
VPERK
Victim Physical Evidence Recovery Kits
DNA samples from victim
Blood Samples- need nurse/doctor, purple-top tubes (EDTA), need to be refrigerated
Buccal Swab Samples
Two saturated buccal swabs
Pre-packaged kits available from the DFS Laboratory
Vaginal/cervix/anal swabs/slides
Hair Samples combs
Clothing collection
Fingernail scrapings/clippings
Other Trace
how are DNA samples collected from victim?
*usually taken under a consent
*Don’t forget to document physical injuries
* Rapes - need samples from all consensual partners
