• What are the characteristics/traits of a good forensic DNA scientist?

The Scientific Method • A procedure used to solve problems or answer questions.

• A way of thinking and looking at the world.

• A technique used to gather information and reach conclusions.

Steps to the Scientific Method

Observation Hypothesis Experiment Then revise the hypothesis Conclusion If the results do not support hypothesis

Principles of Crime Scene Investigation ______ Document the scene ______ Protect the scene ______ Help the victim ______ Search the scene ______ Photograph and draw location of items of evidence ______ Transport evidence to the laboratory ______ Package evidence

Principles of Crime Scene Investigation 1. Help the victim 2. Protect the scene 3. Document the scene 4. Search the scene 5. Photograph and draw location of items of evidence 6. Package evidence 7. Transport evidence to the laboratory

Search the Scene • Goal- “no stone is left unturned.” • Patterns and search strategies – Squares and rectangles – Concentric circles – Pie configuration

Presumptive vs. Confirmatory Tests • Presumptive – Sensitive – Not specific =many false positives • Confirmatory – Less sensitive – Specific =few to rare false positives

• Presumptive – Luminol – Phenolphthalin – Hemastix • Confirmatory – Takayama crystal test – ABAcard Hematrace Blood

Luminol

Luminol

Hemastix

ABAcard Hematrace

Diffusion • Diffusion- the spontaneous tendency of a substance (solute or solvent) to move from a more concentrated to a less concentrated area.

– T or F. Diffusion results in the uniform distribution of a substance.

Spermatozoa • Presumptive – Ultraviolet light – Brentamine reaction • Confirmatory – Christmas tree stain – PSA or P30 – Microscopy

P30 Analysis- ABAcard

Male Reproductive System Prostatic urethra Spongy urethra Membranous urethra

Salivary Glands 23

Saliva • Presumptive – Lugol’s reaction • Confirmatory – Phadebas

Negative test

Phadebas ® Test

Positive test

Fecal Material • Presumptive – Microscopy for undigested materials – Edelman’s Reagent UV • Apple-green fluorescence

• Presumptive – UV Light – Urea • Litmus paper – Creatinine • Jaffe Test Urine