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Shoot-Around 1.Reflect on yesterdays video: how did DNA affect the case? 2.Was the DNA analysis the main evidence that led detectives to the killer? 3.Where did CSI find DNA at the case? How was it preserved? Analyzed?

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Forensic DNA Analysis DNA is the Genetic Material

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Topic: DNA at a Crime Scene Objective: SWBAT identify sources of DNA at a crime scene and how they are preserved and initially analyzed in a lab

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Question: What are the sources of DNA?

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Sources of DNA Blood Semen Saliva Teeth Bone Hair Tissue Feces Urine Skin Cells Sweat

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Where should we look for DNA?

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Critical to Locate Evidence It is important to have good crime scene analysis. Evidence technicians, trained in DNA work, extract material from evidence. (BS in Science) Crime Scene analysts identify evidence at the crime itself. (BS in Criminal Justice) Forensic DNA analysts extract the DNA and perform the reactions and analyze the results. (MS in science)

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A reference sample A reference sample is required to identify matches between DNA. Unless, there is a sample already in the CODIS system, we will need to find one!

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Reference Samples Blood Blood transfusions Buccal Swabs/Saliva Clothing Last resort secondary standard Other Secondary Standards Toothbrush, hairbrush, glasses, etc. Other standards All persons who had access to a crime scene should be documented May be necessary to collect samples from these individuals

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How do we process the evidence?

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Case Processing Includes: Location and Collection of Evidence Collection Techniques Preservation of Evidence Packaging and Storage Documentation-Chain of Custody Casework Analysis

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Protect the Evidence Preserve evidence with proper packaging Proper storage Use appropriate labels BIOHAZARD LABELS Case#, Initials, Descriptive label, date packaged Sign across your seal!!

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Evidence Handling Never collect evidence without documenting the location, conditions, etc first Sketches, photographs, detailed notes The fewer people who handle evidence, the better Decreases chance of contamination Assists in court admissibility hearing

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Chain of Custody A record of individuals who have had PHYSICAL possession of the evidence Critical in maintaining the integrity of the evidence If DNA analysis results in a foreign DNA type, it may be necessary to identify persons who handled the evidence

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Chain of Custody Components Identifiers that describe the evidence at the time it was found Location Position Date/Time of Collection Packaging/Sealing information

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Multi-Section Cases Many items need to go through other sections of the lab Common requests: Latent Prints Trace / Microanalysis Firearms Important to decide based on case, which evidence has priority

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How Can Evidence Become Contaminated?

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Actions to Avoid Touching any areas/items where DNA may exist Touching your face, nose, hair, and mouth when collecting and packaging evidence Sneezing, coughing, excessive talking near evidence Gloves and or masks should be changed if contaminated

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Summary In the summary box, write 2-3 that summarizes this section. Make sure to reference where DNA is located, preserved, and processed.