1. JS 113: Detection, Collection, Presumptive testing and Preservation of Biological Evidence
Pre-class activities
Quiz
Announcements and Assignments for next week
Learning Objectives
List the sources of Biological Evidence
Discuss presumptive tests utilized on biological evidence
Discuss proper collection of biological evidence
Understanding how to avoid contamination
Understanding how to detect and monitor for contamination

2. Announcements & Assignments
Assignments and Announcements
Visit the following document on collection of biological evidence-
Each team member should take a section and summarize it in 300 words. Write a total of 5 questions and answers based on your reading
10/31 Laboratory 5A – Serology – Presumptive Testing for biological fluids
11/05 Student Led Review for Exam 2 :
C5-Org, 6 Inor, 8 trace, 9 drugs, 10 tox, 12 serology, 15 impression, Tom Abercrombie(with 9) and Sandra Sachs (with 10)lectures- Shoeprint lab (with 15), Trace lab (with 8)
11/07 Exam 2
References
Forensic DNA Analysis. Rudin, N. and K. Inman. 2nd Edition ISBN: Publisher: CRC Press; 2nd edition (December 21, 2001) C1 and C2
Forensic DNA Typing: Biology and Technology Behind STR Markers John Butler PhD ISBN: X Academic Press –Figure and references on DNA sources
Saferstein R Chapter 3
Gary Sims- Personal communication Powerpoint slides on contamination
Jeremiah Garrido- Santa Clara County Crime Laboratory

3. Biological Fluids ? What are they? Forensic Value ?
Cells
Most commonly analyzed
BODY
FLUIDS
Cell Types
Blood
White Blood Cells
Semen
Spermatozoa
Saliva
Skin Cell

4. The Nature of Blood
Blood- A complex mixture made of cells, enzymes, proteins and inorganic substances
Liquid portion (55%) : Water
Solid portion (45%) :
Red blood cells, white blood cells, platelets
Serum: Liquid containing antibodies that separates from blood when a clot forms

5. Nature of Blood: Function
Red blood cells (RBC):
Transports oxygen from lungs to body tissues and in turn removes carbon dioxide by taking it to the lungs.
Also contain
Antigens:
proteins found of the surface of RBCs that stimulates the body to produce antibodies against it
Grouped into systems
ABO blood typing

6. Antigen & Antibody Components of Blood
For every antigen there is a specific antibody
Blood Type
Antigens
(on Red Blood Cells)
Antibodies
(in Serum) A
Anti-B B
Anti-A AB
Anti-A nor Anti-B O
A nor B
Anti-A & Anti-B

7. Blood as Physical Evidence
Occurrence of a blood stain in a certain place
on an item may substantiate an account of a crime
Bloodstain Pattern Interpretation:
Shape, position, size or intensity of a bloodstain
may support a particular sequence of events
DNA typing analysis can be used to eliminate
whole groups of people as suspects

8. Shape,
Position,
Size ?

9. Neck incisions (scene)

10. Forensic Characterization of Bloodstains
IS THIS STAIN BLOOD?
WHAT SPECIES?
IF HUMAN ORGIN WHO DEPOSITED THE BLOOD?

11. Forensic Characterization of Bloodstains
Three ways of characterizing a possible bloodstain:
Chemical Color Tests or Crystal Test
Based on presence of hemoglobin
Species Determination
Based on Antigen-Antibody Reaction
Individualizing bloodstain
DNA analysis and calculating statistics

12. Forensic Characterization of Bloodstains: Is This Blood??
Chemical color tests
Based on hemoglobin's peroxidase-like activity (Peroxidase: enzyme that oxidizes organic compounds)
Ex: Lab/phenolphthalein, O-tol
Crime Scene/Hemastix
Advantage: very sensitive
Disadvantage:
false positive rxn
Potato/Horseradish
Strong oxidizers like bleach

13. Forensic Characterization of Bloodstains cont’d
Luminol Test
Produces light rather than color
Typically sprayed onto suspected stains to reveal stains & patterns
LIGHT EMISSION

14. STAIRCASE INTO BASEMENT
Can we say it’s human blood?
LIGHT EMISSION