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Chapter  10:  Crime Chapter  10:  Crime

Chapter 10: Crime - PowerPoint Presentation

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Chapter 10: Crime - PPT Presentation

Chapter 10 Crime Scene Investigation Textbook pag e 167 I Introduction A Forensic science begins at the crime scene B Four steps of Crime Scene Investigation CSI Recognitionscene survey documentation collection ID: 772717

scene crime csi evidence crime scene evidence csi general cont procedures eyewitness http items www packaged sketch collection search

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Chapter 10: Crime Scene Investigation Textbook page 167

I. IntroductionA. Forensic science begins at the crime scene.B. Four steps of Crime Scene Investigation (CSI)Recognition—scene survey, documentation, collectionIdentification—comparison testingIndividualization—evaluation, interpretationReconstruction—reporting and presentation

C. A main goal of CSI is to successfully identify and preserve physical evidence.1. Two general types of evidence: direct and physicalDirect/testimonial = evidence in the form of a statement made under oath.(go to eyewitness slides)Physical evidence = any and all objects and materials that are relevant in a crime (examples: drugs, toxic substances, paints, gunshot residues, firearms and ammunition, impressions, petroleum products, blood, fibers, glass, hair, body fluids, fingerprints, etc.)I. Introduction (cont.) VS.

Direct/testimonial evidence extension activity Note: The next 10 slides came from The Science Spot websitehttp://sciencespot.net/Pages/classforsci.html#crimescene

Testimonial evidence includes oral or written statements given to police as well as testimony in court by people who witnessed an event. Eyewitness accounts can be a useful tool in helping investigators with analyzing a crime scene, but are not viewed to be highly reliable. In addition, eyewitness identifications (right or wrong) can have a big influence on the outcome of an investigation or trial. People are likely to view the same scene in different ways depending on their positions, line of sight, familiarity with the area, and other factors that can interfere with a person’s ability to remember details.What is testimonial evidence?

Directions:You will have 30 seconds to view the next screen. Try to memorize all 20 items you see!You are NOT allowed to write anything down You CANNOT talk to anyone else.Memory Challenge

Neuroscience for Kids - http://faculty.washington.edu/chudler/puzmatch1.htmlItems to remember ...

What do you remember?You have 2 minutes to list as many of the items as you can!How did you do?All 20 – Awesome 15-19 – Great10-14 – Pretty swell5-9 – Could be better 4 or Less – Wake up

According to The Innocence Project (2008) "Eyewitness misidentification is the single greatest cause of wrongful convictions nationwide, playing a role in more than 75% of convictions overturned through DNA testing." Still, the criminal justice system profoundly relies on eyewitness identification and testimony for investigating and prosecuting crimes (Wells & Olson, 2003).Source: http://www.helium.com/items/1276135-accurate-eyewitness-accountsDid you know?What factors affect a person’s memory and their ability to identify a suspect?

Age may play a role in the accuracy of an eyewitness’ statement or identification of a suspect. Studies have shown that when a lineup contains the actual culprit, both young children and elderly perform well, but when the lineup does not contain the culprit there is a higher rate of mistaken identifications.The race of the witness may also play a role. The Cross Race Effect (CRE) is a phenomenon in which people are better at recognizing faces of their own race rather than those of other races.The use of drugs can alter a person’s ability to recall the events of a crime even after they are no longer under the influence.A person’s memory of an event can be influenced by other witnesses, investigators, and/or the media. Investigators use open-ended questioning and follow procedures for conducting line-ups to limit their influence on a witness’ memory of an event or identification of a suspect.Witness FactorsSource: http://www.helium.com/items/1276135-accurate-eyewitness-accounts

A crime that is extremely traumatic for an eyewitness may affect his/her recall of the event. For example, a witness confronted with a weapon tends to focus on the weapon rather than the perpetrator’s face.Someone who is able to focus on a perpetrator's face for a minute or longer will tend to have a more accurate memory than someone who saw the person for only a few seconds. Studies have shown that faces that are either highly attractive, highly unattractive, or distinctive are more likely to be accurately recognized. Simple disguises, such as hats or sunglasses, can interfere with accurate eyewitness identification. However, body piercings and tattoos increases the likelihood of an accurate identification.The time of day in which the crime occurred as well as a person’s view of the scene may affect what a he/she is able to see. In addition, a person who is familiar with the area in which the crime took place, may have a better recall of the positions of the victims or suspects. Crime Scene & Suspect FactorsSource: http://www.helium.com/items/1276135-accurate-eyewitness-accounts

Crime Scene ChallengeNow that your eyes and brain are warmed up, let’s test your observation skills a bit more.You will have 2 minutes to study the photograph of a crime scene on the next slide. Try to pay attention to details as you will be asked 10 questions about the crime scene!You are not allowed to write anything down until after the time is up.Ready?

Answer each question below.1. What color coffee mug was in the picture? Blue Red Yellow  2. When was the deadline? Yesterday Today Tomorrow  3. What time was on the clock on the wall? 10:40 11:05 1:55  4. How many sticky notes were on the whiteboard? Four Six Eight 5. Which of the following was NOT in the picture? Stapler Trash Can Printer 6. What was the name on the plaque on the desk? Bill Brian Carl   7. What color was the victim's shirt? Black Blue Red   8. How many plants were in the picture? None One Two 9. What was the color of the marker in the desk drawer? Red Blue Green 10. Where was the book in the picture? On a box In the trash can Under the body Source: http://forensics.rice.edu/html/picture_begin.html

2. Use of physical evidenceProve that a crime has been committedCorroborate testimonyLink a suspect with a victim or with a crime sceneEstablish the identity of persons associated with a crimeAllow reconstruction of events of a crime

II. Defining a crime sceneCrime scene are diverse and unique . . . no two scenes are exactly the samehttp://www.exposay.com/celebrity-photos/crime-scene-4th-shooting-in-hacney-within-2-weeks-1uvxtj.jpghttp://www.srpublications.com/criminology/item/D/images_D/crime_scene_reconstruction.jpg

Classification of crime scenes can be based on . . .locationprimary: site of original or first criminal activitysecondary: any subsequent sites of criminal activitysizemacroscopic crime scene: composed of many crime scenes (overall area)microscopic crime scene: focused on specific types of physical evidence found at the macroscopic crime sceneII. Defining a crime scene (cont.)type of crime committedhomiciderobberysexual assaultetc.condition of the crime sceneorganized disorganizedphysical location of crime scene indoors outdoors vehicle etc. others Note : Each crime scene can be a combination of these classifications. Also as an investigation proceeds, the definition of the crime scene can be constantly modified .

III. General procedures for CSI (recognition step)Secure and protect the crime sceneFirst responding officercritical roleresponsibilities include:assist the victimsearch for and arrest suspects if possibledetain all witnessesprotect and secure the scenenote and communicate to investigators all movements and alterations made to the scenehttp://www.fundraw.com/clipart/clip-art/00000898/Police-Officer/

Establish crime scene securityWhy? Locard’s PrincipleMulti-level approachIII. General procedures for CSI A. Secure and protect the crime scene (cont.) James, S.H., & Nordby , J.J. (2005). Forensic Science: An Introduction to Scientific and Investigative Techniques . 2 nd Edition. New York: Taylor & Francis. Pg. 171. http://shine4ever.files.wordpress.com/2009/08/crime-scene-tape-police-lights.jpg

Survey the scene“Walk-through”Note: transient (temporary) or conditional (the result of an action) evidence, points of entry and exit, and initial observations Documenting a crime scene Four main components = notes, photography, videotape, sketch (see concept map or web for explanations)III. General procedures for CSI (cont.)

Crime Scene SearchesPreliminary searchdone once the scene is securedpurpose = note obvious evidence Post-documentation searchintensive search for less obvious/overlook evidencecompleted before collection and packaging of evidenceevidence found must be documented before collectionIII. General procedures for CSI (cont.)

Search methods/patternsPurpose = provide systematic search so no evidence missedOrganized = everyone on same page and stress no touching or altering evidence (just mark they are there)Six most common search patternsLinkLine or StripGridWheel or RaySpiralZoneIII. General procedures for CSI D. Crime Scene Searches (cont.)

Crime scene search patterns 1. L ink 2 . Line or strip 3 . Grid 4 . Wheel or Ray 5. Spiral 6 . Zone 1 2 3 4

Collection of EvidenceDone AFTER crime scene documentation and intensive search for evidenceEvidence collector = one person given this job --Why? To ensure evidence collected, packaged, marked, sealed, and preserved in CONSISTENT mannerOrder of collectionno set orderdepends on nature of the evidence --example: transient, fragile, or easily lost evidence collected firstIMPORTANT: if any new evidence discovered, must first DOCUMENT it before collectingIII. General procedures for CSI (cont.)

General collection guidelinesMost items packaged in primary container, then placed inside secondary containerOuter containercompletely sealed at time of collection with tamper-resistant tapemarked with: items contained; ID of collector; time, date, and location of collectionEach item packaged SEPARATELY to prevent cross-contaminationIII. General procedures for CSI E. Collection of Evidence (cont.)http://www.fbi.gov/publications/leb/2006/april2006/page25.jpg

Ways to package different categories of evidence Biological material --packaged in a dry paper bag (NOT plastic)Trace evidence (hairs, fibers, etc.) --packaged in small envelops or tins --Druggist’s folds used as primary container = pieces of paper folded around items to hold trace evidence in place before placed in outer containerFingerprints --lifted fingerprints are attached to an index cardArson debris -- packaged in old paint cans or mason jars (sealed glass jar)Castings --packaged in a box with cushioningIII. General procedures for CSI E. Collection of Evidence (cont.) http://www.shenet.org/High/hsacaddept/science/jstdenis/Forensic%20Science/PowerPoint%20Presentation.swf

Crime Scene ReconstructionThe process of analyzing data to ultimately develop a theory of the crimeStages involved (see diagram and explanations on page 180 of textbook):Data collectionConjectureHypothesis formationTestingTheory formationIII. General procedures for CSI (cont.)

Crime scene sketching directionsCrime scene sketching example Crime Scene sketching methods

Crime Scene SketchingCS sketching is the final step in CS documentationProvides for dimensional relationships2 viewsBird’s eye view (top-down/overhead . . .most common)Elevation view (side-on)2 typesRough sketch—completed at scene, not to scaleFinal sketch—completed later with lots of time and detail, drawn to scale

4 techniques for measuring evidenceTriangulation (indoor)Rectangular coordinates (indoor)Baseline (outdoor) Polar coordinates (outdoor) RP RP evidence RP evidence evidence evidence evidence RP evidence RP

CS Sketching Lab TipsLabel NorthLabel RPUse rectangular coordinates to measure evidenceSymbolsEvidence in final sketch:Draw in body only, for all others use LETTERSMeasure to center of objectDo not include evidence measurements in sketch, they will be in your evidence table Use RULER in final sketch and tables Final sketch drawn to SCALE (include key to scale) Evidence table Use detail when including item description ( ie . Book . . . What book? Size?—measure dimensions) Letter Item/description Location From N From W A B C Body window door

CS Sketch Example= 1foot