Evidence Collection and Crime Scene Investigation

Evidence Collection and Crime Scene Investigation1EvidenceObjective: Differentiate between the different types of evidence

Do Now: Is blood evidence 100% conclusive? Have students only copy the notes that are in red2 Locards Exchange PrincipleWhen a person comes into contact with an object or another person, a cross-transfer of physical evidence can occur.

Have students make their own definition3Types of Evidence

Types of EvidenceDirect: firsthand observations (eyewitness account, video camera, confessions) shows that something is a fact without inference or presumption

Types of EvidenceCircumstantial: indirect evidence; implies a fact, but does not directly prove it requires making an inferenceTrace Evidence:Physical bullets, weapons, impressionsBiological body fluids, plant parts, hairTrace EvidenceSmall but measurable amounts of physical or biological material found at a crime scene

Examples of Trace EvidenceHairFibersSoilfingerprints

Body fluids (semen, blood, saliva, mucus)Paint chipsBroken glassChemical residue

Categories of EvidenceClass EvidenceNarrows identity to a group of persons or thingsExample: blood typeIndividual EvidenceNarrow identity to a single person or thingExample: fingerprintYour TaskIn your groups complete Identifying types of evidence activity. Answers 10ClosureIdentify what evidence you can collect at this scene State whether its biological or physical then state if its class or individual.

Objective: Problems with evidence collectionDo Now: Can you convict someone on circumstantial evidence alone?

Case Studyhttp://www.youtube.com/watch?v=dr6uTw2Eh6M

Complete the case study on OJ SimpsonObjective: Observe Locards Principle Do Now: What led to OJ Simpsons acquittal? Objective: proper evidence collection techniquesDo Now : What is trace evidence?Complete the locards principle lab in your groups. Materials for lab (cloth swatches or white socks or cotton balls) crime scene swatches from three different locations that students can pick from. See marty palermo in rm 247 for further description of how to set up lab17Your cloth swatches go in ziplock bags (number them with CS#)Analyze each with magnifying glass etc. and take notes/observations.Obtain a crime scene evidence bag from Mr. PalermoAnalyze the sock in evidence bag and match it to one of the crime scenes based on your notes/observations Objective: how to process a crime sceneDO NOW: Why is it important to photograph a crime scene?The Crime Scene Investigation Team Who is at the crime scene? Police and possibly a district attorney. Crime scene investigators. Medical examiners. Detectives. Specialists. The Seven Ss of Crime Scene InvestigationSecure the scene. Separate the witnesses. Scan the scene. See that photos are taken. Sketch the scene. Search for evidence. Secure the collected evidence.

1. Secure the Scene

2. Separate the WitnessesDo not allow witnesses to talk to each otherWitness accounts will be comparedAvoid witnesses working together to create a storyAsked: who, what, where?

3. Scan the sceneDetermine primary and secondary crime scenesPrimary: where murder took placeSecondary: where corpse was foundWhere should photos be taken?Wear protective gear to prevent contamination of crime scene

Marking Evidence

4. See that photos are taken Show the scene exactly as it was when you first saw itIf something was moved before you arrived, dont try to reconstruct the scene just take the pictures the way you see itBe careful not to destroy any evidence while taking photos

Discuss 360 sanners that create virtual crime scene27Overall Shots Outside the Scene

Exit (door)First shot entering door:Outside science officeOverall Shots Inside the Scene

Evidence: Knife (possible weapon)

Midrange PhotoClose-Up (with ruler)5. Sketch the Crime SceneMake accurate rough sketchNote direction (N) and scale of distanceInclude relevant objects (body, doors, windows, furniture, immovable landmarks)Make final copy for court

Rough sketch

Final Sketch

6. Search for evidenceGrid, strip or lane, spiral search patternUse flashlight to find hair and fibersUse forceps, vacuum cleaner to collect evidence

GridStrip or LaneSpiral7. Secure the EvidenceProperly package, seal, and label ALL evidence!Liquid: airtight, unbreakable containersWet items (biological): dry out in breathable containerDry item: bindle plastic or paper containerSeal with tape and labeled with pertinent info

Demonstrate how to package evidenceA Bindle is folded paper for small amounts of trace evidence35The Chain of CustodyIn order to present credible evidence in court, a chain of custody log is essential. (in real life there is more involved but for this class do as follows) Bag evidence (seal, sign and date)Fill out evidence log every time you open it.

Processing the crime scencehttp://www.youtube.com/watch?v=ur1GxXZGnNI

Objective: Sketch a crime sceneDO NOW: What happens if the chain of custody is broken for a piece of evidence? Rough Sketch QuestionsUsing the rough sketch complete the questions. No digital copy of this activity39Lab Sketching the Crime SceneIn your groups complete the lab on sketching the crime scene.Divide up the work. Have some members:Take measurementsSketch

Set up an area in your room as a crime scene. Make a tape outline on the floor representing a body. Put 2-4 pieces of evidence near the body. Students will need plain paper, meter sticks, rulers, graph paper a compass (most have one on their phone) 40Objective: finish crime scene sketchDo now: Why does each piece of evidence have 2 measurements going to it? (triangulation)

Quiz tomorrow on units 1 and 2 (look over your notes)Objective: finish crime scene sketchMake sure that you have done the following:1 rough sketch 1 final sketch (scaled) Each piece of evidence has 2 measurements going to itKey or legend North indicated on sketchLocation, date of drawing Objective: Case StudyDO NOW: In your crime scene sketches, why is it important to show which direction North is?

Hand in crime scene labObjective: Case StudyComplete the woodchipper case study.

Evidence Recovered

ConclusionWhat was the outcome of the case?