JS 112: Detection, Collection, Presumptive testing and Preservation of Biological Evidence I.Pre-class activities A.Group Quiz B.Announcements and Assignments II.Learning Objectives A.List the sources of Biological Evidence B.Discuss presumptive tests utilized on biological evidence C.Discuss proper collection of biological evidence D.Understanding how to avoid contamination E.Understanding how to detect and monitor for contamination

Announcements & Assignments Announcements – Weds 28 th Dr. John Tonkyn Assignments – Read Chapters 10 and 11 – View the following trainings – What Every First Responding Officer Should Know About DNA Evidence AND – What Every Investigator and Evidence Technician Should Know About DNA Evidence – Find the training at – - References – Saferstein R Chapter 10 and 11 – Gary Sims- Personal communication Powerpoint slides on contamination – – Jeremiah Garrido Slides on presumptive testing- Santa Clara County Crime Laboratory

Sources of Biological Evidence Extra Credit Everyone that signed their team lists will get +1 Members of the two top teams get +2 Bonus points still being recalculated

Blood and blood stains Budowle 1995 Semen and semen stainsBudowle 1995 BonesGill 1994 TeethAlvarez 1996 Hair with rootHiguchi 1988 Hair shaftWilson 1995 Saliva (with nucleated cells)Sweet 1997 UrineBenecke 1996 FecesHopwood 1996 Debris from fingernailsWiegand 1993 Muscle tissueHochmeister 1998a Cigarette buttsHochmeister 1991 Postage stampsHopkins 1994 Envelope sealing flapsWord 1997 DandruffHerber 1998 FingerprintsVan Oorschot 1997 Personal Items: Razor blade, chewing gum, wrist watch, ear wax, toothbrush Tahir 1996 MaterialReference Sources of Biological Evidence

Steps in Forensic DNA typing (Figure 6.1 Rudin and Inman 2001) Evaluation- Is it there? 1. Start with biological sample 2. Screen- blood? Semen? Saliva, human? Extraction- Get and clean DNA 3. Open cells  Get DNA 4. Methods to get DNA and purify DNA Quantify- Determine quality and quantity? 5. Quantify- How good and how much did you get? Type to determine and compare alleles 6. RFLP vs PCR 7. Determine alleles and compare DNA types Or alleles present in samples and references Interpretation of Results

Real Forensic Biologists must first screen evidence for biological fluids before DNA testing: The “Art” of Forensic Science What are they? Forensic Value ? – Cells Most commonly analyzed BODY FLUIDS Cell Types Blood White Blood Cells Semen Spermatozoa Saliva Skin Cell

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

Blood spatter patterns may be used to determine the position of the source Where are the o drops coming from?

Pointed end of a Bloodstain points in the direction of travel

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

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

Some stains are easily detected