4 Are there cars parked on the sides of the road? What color is the pickup truck driving in the road?Any minivans around?What does the blue sign say?What’s the speed limit?Are there any pedestrians on the road?
5 Locard’s Exchange Principle When a person comes into contact with an object or another person, a cross-transfer of physical evidence can occurHair, skin cells, clothing fibers, pollen, glass fragments, debris from clothing, makeup, soilCalled trace evidencepet hair on clothesHair on your brushFingerprints on glassSoil tracked into houseDrop of blood on t-shirtUsed tissuePaint chipsBroken glassFiber from clothing
6 Evidence Classified two different ways – Direct evidence Circumstantial evidencePhysical evidenceBiological evidenceTrace evidence
7 Direct EvidenceFirsthand observations such as eyewitness accounts or police dashboard video camerasConfessionsTestimony by a witness in court
8 Circumstantial Evidence Indirect evidence that can be used to imply a fact but that does not directly prove itLink between crime scene and a suspectPhysical – Impressions, fingerprints, footprints, shoe prints, tire impressions, tool marks, fibers, weapons, bullets, shell casingsReduces number of suspects to a specific, smaller groupBiological – body fluids, hair, plant parts, natural fibersMakes the group of suspects very small, or reduces it to a likely individual
9 Class vs. Individual Evidence Class – narrows identity to a group of persons or thingsEx – blood typeIndividual – narrows an identity to a single person or thingEx – fingerprints
10 The CSI Team Police officers District attorney Crime scene investigatorsMedical examinersDetectivesSpecialists
11 The Crime Scene Investigation Team Police officers – secure the sceneDistrict attorney – determine whether search warrant is necessaryCrime-scene investigators – document crime scene in detail and collect physical evidenceRecorders, sketch artists, photographers, evidence collectorsMedical examiners – determine cause of death if homicideDetectives – look for leads by interviewing witnesses and talking to crime-scene investigators about evidenceSpecialists – consulted if the evidence requires their expertiseEntomologists, forensic scientists, forensic psychologists, etc.
12 The Seven S’s of Crime Scene Investigation Securing the sceneSeparating the witnessesScanning the sceneSeeing the sceneSketching the sceneSearching for evidenceSecuring and collecting evidence
13 1. Securing the SceneResponsibility of the first responder (usually a police officer)Restricts all persons not authorized from enteringSecurity log of all entering and exitingMay request various experts to be sent to sceneFirst Priority – safety of all individualsSecond Priority – preservation of evidence
14 2. Separating WitnessesWitnesses must not be allowed to talk to one another!Questions to ask:When did the crime occur?Who called in the crime?Who is the victim?Can the perpetrator be identified?Where were you when you observed the crime scene?
15 3. Scanning the SceneScan the scene to determine where photos should be takenPrimary crime scene – where crime took placeSecondary crime scene – location linking to crimeEx: Primary scene - front of store where robbery took placeSecondary scene – home of suspectEx: Primary scene – location of murderSecondary scene – location where corpse was found
16 4. Seeing the Scene Crime examiner needs to see whole scene NEEDS TO BE IN UNALTERED POSITION!!!Photos of overall areaClose-up photosPhotos with and without a measuring rulerView of crime scene from different angles and distancesClose-up photos of any evidence and bodiesPhotos need to be taken before evidence or body is moved
38 5. Sketching the SceneRough sketch – notes position of body and any other evidenceAll objects measured from two immovable landmarksNorth should be labeled, scale included for distanceDoors, windows, furnitureIf outdoors, position of trees, vehicles, hedges, other structuresDrawn AT the sceneAlso include – name, date, location, conditions outside or inside
39 Figure 2–4 Rough-sketch diagram of a crime scene Figure 2–4 Rough-sketch diagram of a crime scene. Courtesy Sirchie Finger Print Laboratories, Inc., Youngsville, N.C.,
40 5. Sketching the SceneFinal Sketch – include all the aspects of a rough sketch but more accuratePossible for presentation in courtComputer programs available nowDrawn in the lab AFTER searching the crime sceneNote-taking also occurs throughout entire process
41 Figure 2–5 Finished-sketch diagram of a crime scene Figure 2–5 Finished-sketch diagram of a crime scene. Courtesy Sirchie Finger Print Laboratories, Inc., Youngsville, N.C.,
42 6. Searching for evidence Scene should be walked and location of evidence marked, photographed, and sketchedPatterns:SpiralGridLinearQuadrant or ZoneSingle investigator – grid, linear, or spiral patternGroup of investigators – linear, zone, quadrant
44 7. Securing and Collecting Evidence All must be properly packaged, sealed, and labeledLiquids and arson – stored in airtight, unbreakable containerBiological evidence – stored in breathable containers so air can dry outWet evidence – stored in paper and allowed to air dryNEVER place wet evidence in an airtight container; will cause mold and degrade DNAPaper bindle – paper used to store evidencePlaced into evidence bag and labeled
45 StandardsThere are many standards for collecting different types of evidenceExample: National Institute of Justice
46 Control Samples Obtained from the victim for the purpose of exclusion Ex - blood samples found on a victim or at crime scene compared to victim’s bloodIf they match, sample is victims and no further tests runIf not, may have come from suspect and further testing is completed!
47 Evidence Log Case number Item inventory number Description of evidence Name of suspectName of victimDate and time of recoverySignature of person recovering evidenceSignature of any witnesses present during collection
48 Chain of CustodyEach person who handles the evidence must be recorded properlyWhen evidence is found – marked with proper information and placed in a collection bagContainer is sealed and collector’s signature is written across sealed edgeNext person responsible opens at a location other than sealed edge, completes exam, reseals in new packaging and signs chain of custody log!Pattern continues!
49 Chain of Custody EXTREMELY important for courtroom! All who handled evidence could be asked to appear in courtProcess must show evidence was handled properly and every person handling it was recorded
51 Analyze the EvidenceFBI crime lab is one of largest forensic labs in the world!Forensic Lab Technicians – specialized and process only one type of evidenceLead detective – lab results sent to himLooks at evidence and attempts to determine how it fits into overall crime scenarioMust consider all possible interpretations for evidence
52 Use of Evidence Evidence compared to witness’ statements Can link a suspect to scene or a victimEstablish the identity of a victimConfirm verbal witness testimonyAcquit the innocent
53 Crime Scene Reconstruction Forms a hypothesis of the sequence of events from before the crime was committed through its commissionEvidence does not lie, but could be staged!Evidence is used to determine overall crime scenario
54 Crime Scene Safety THE CRIME SCENE The increasing spread of AIDS and hepatitis B has sensitized the law enforcement community to the potential health hazards that can exist at crime scenes.In reality, law enforcement officers have an extremely small chance of contracting AIDS or hepatitis at the crime scene.The International Association for Identification Safety Committee has proposed guidelines to protect investigators at crime scenes containing potentially infectious materials that should be adhered to at all times.THE CRIME SCENE
55 Crime Scene SafetyAt crime scenes where blood or body fluids involved: latex gloves and shoe coverings should be warn.If potentially infectious dust or mist encountered: particle mask/ respirator, goggles, or face shield recommended also.Personnel should be aware of sharp objects, knives, hypodermic syringes, razor blades, etc and place them in appropriate container with label.Red biohazard bag should be used for disposal of contaminated gloves, clothing, masks, pencils, etc. and removal to approved biohazardous waste pickup.
56 Crime Scene Safety5. Note-taking should be done while wearing uncontaminated gloves to avoid contamination or pens, pencils, notebook, paper, etc.6. If personal protective equipment (PPE) becomes torn, must be removed immediately and person must decontaminate the potentially contaminated body area with recommended solution.No eating, drinking, smoking, or applying makeup at scene of a crime.All nondisposable items (lab coats, towels, personal clothing) that may be contaminated are placed in a yellow plastic bag, labeled “Infectious Linen” and laundered by a qualified service.