The Crime Scene. Catalyst 10/1/13 Question: Differentiate between class and individual evidence....
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Transcript of The Crime Scene. Catalyst 10/1/13 Question: Differentiate between class and individual evidence....
Catalyst 10/1/13Catalyst 10/1/13
Question: Differentiate between class Question: Differentiate between class and individual evidence.and individual evidence.
Answer: Answer:
Locard’s PrincipleLocard’s Principle
Dr. Edmond LocardDr. Edmond Locard Director of the world’s first forensic Director of the world’s first forensic
lab in Francelab in France Came up with the idea that when a Came up with the idea that when a
person comes into contact with an person comes into contact with an object or another person, a object or another person, a cross-cross-transfertransfer of physical evidence of physical evidence can can occur.occur.
EvidenceEvidence
Main types (continued)Main types (continued) 1-Direct evidence1-Direct evidence 2-Circumstantial evidence2-Circumstantial evidence
Trace evidenceTrace evidenceClass evidenceClass evidence Individual evidenceIndividual evidence
DirectDirect Evidence Evidence Consists of Consists of firsthandfirsthand observationsobservations In court, this evidence involves testimony by In court, this evidence involves testimony by
a witness about what that witness personally a witness about what that witness personally saw, heard, or did. (NO intermediary, directly saw, heard, or did. (NO intermediary, directly from example to the investigator)from example to the investigator)
Examples:Examples: Eyewitness accountsEyewitness accounts Police dashboard videoPolice dashboard video ConfessionsConfessions
CircumstantialCircumstantial Evidence Evidence
IndirectIndirect evidence that can be used evidence that can be used to imply fact but does not directly to imply fact but does not directly prove itprove it
May provide a May provide a linklink between a crime between a crime scene and a suspectscene and a suspect
OnlyOnly suspect and victim actually see suspect and victim actually see it left at crime sceneit left at crime scene
Can be physical or biologicalCan be physical or biological
CircumstantialCircumstantial Evidence (cont) Evidence (cont)
ExamplesExamples:: Finding a suspect’s gun at the site of a Finding a suspect’s gun at the site of a
shootingshooting Biological evidence:Biological evidence:
Body fluids, hair, plant parts, and natural Body fluids, hair, plant parts, and natural fibersfibers
Physical evidence:Physical evidence: Fingerprints, footprints, shoe impressions, Fingerprints, footprints, shoe impressions,
tire impressions, bullets, and tool markstire impressions, bullets, and tool marks
TraceTrace Evidence Evidence (type of Circumstantial)(type of Circumstantial)
Type of Circumstantial evidenceType of Circumstantial evidence Physical transfer of materialPhysical transfer of material ExamplesExamples::
HairHair FingerprintsFingerprints SoilSoil BloodBlood KleenexKleenex FiberFiber GlassGlass Paint chipsPaint chips
ClassClass Evidence Evidence (type of Circumstantial)(type of Circumstantial) Narrows an identity to a group of Narrows an identity to a group of
persons or thingspersons or things CannotCannot specify a single person specify a single person Only excludes people that do not fit Only excludes people that do not fit
the categorythe category Examples:Examples:
Blood typesBlood types Hair colorHair color Common fibersCommon fibers Shoe printsShoe prints
IndividualIndividual Evidence Evidence (type of Circumstantial)(type of Circumstantial)
Narrows identity to a single person or Narrows identity to a single person or thingthing
Examples:Examples: DNADNA Complete fingerprints(not partials)Complete fingerprints(not partials) Tool marksTool marks Anything torn or broken and left at the Anything torn or broken and left at the
scenescene
Catalyst 10/2/13Catalyst 10/2/13
Question: What is the difference Question: What is the difference between circumstantial and direct between circumstantial and direct evidence?evidence?
Answer:Answer:
Forensic Activity-ROBBERY!Forensic Activity-ROBBERY!A large appliance store was robbed, but no forced entry was apparent. A tab from a beverage can was found by one of the outside doors, causing investigators to assume that it may have been used to wedge the door for later access. The next day, the driver of a vehicle was pulled over for a minor traffic violation. In the car were a number of empty soda cans, all with their tabs removed.
Answer in your groups!Answer in your groups! Can you verify that whoever robbed the store worked
there? Explain your answer. Did the robber have some connection to anyone that
worked there? Explain your answer. Can the tab found at the crime scene be associated with
the empty soda cans in the suspect’s car? Why or why not?
How would you go about trying to individualize the tab to the can?
How strong of a case can you, the forensic investigator, establish against the suspect? Explain your answer.
What kind of evidence is the tab; class or individual? Explain your answer.
What additional evidence could be collected from the tab that was left at the crime scene to strengthen this case? Explain how your answer would help the prosecution.
5 S’s of Crime Scene 5 S’s of Crime Scene InvestigationInvestigation
Securing the sceneSecuring the scene Separating the witnessesSeparating the witnesses Scanning the sceneScanning the scene Sketching and photograph the sceneSketching and photograph the scene Searching and collecting of evidenceSearching and collecting of evidence
1-Securing the Scene1-Securing the Scene
The most important job at a crime The most important job at a crime scenescene
Performed by the first officer at the Performed by the first officer at the scene, called the scene, called the first responderfirst responder
Safety of all individuals in first prioritySafety of all individuals in first priority Preservation of evidence is secondPreservation of evidence is second Finally record the sceneFinally record the scene
2-Separate the witnesses2-Separate the witnesses
Separation prevents them talking to Separation prevents them talking to each othereach other
Each witness will be asked about the Each witness will be asked about the crime scene and what they observedcrime scene and what they observed
3-Scan the Scene3-Scan the Scene
Determine if and where photos Determine if and where photos should be takenshould be taken
Determine if there may be a Determine if there may be a secondary crime scenesecondary crime scene Person killed at a party (primary scene)Person killed at a party (primary scene) Dumped in a lake (secondary scene)Dumped in a lake (secondary scene)
4-Sketching the Scene4-Sketching the Scene
First is a Rough Sketch done at the sceneFirst is a Rough Sketch done at the scene Must be Must be accurateaccurate and and to scaleto scale Note body, evidence, doorways, windows, Note body, evidence, doorways, windows,
walls, trees, cars, and movable objectswalls, trees, cars, and movable objects Distances should be measured and Distances should be measured and
recordedrecorded Case number, date, location, and time Case number, date, location, and time
should also appear on the sketch should also appear on the sketch
FinalFinal Sketch Sketch
Usually done by a computerUsually done by a computer Presented in courtPresented in court
Photographing the Photographing the Crime SceneCrime Scene
Photograph:Photograph: All evidenceAll evidence Doors and Doors and
windowswindows Anything out of Anything out of
the ordinarythe ordinary
5-Searching and Collecting 5-Searching and Collecting EvidenceEvidence
Must be properly packaged, sealed, and Must be properly packaged, sealed, and labeledlabeled
Dry evidence Dry evidence - placed in a paper bindle, - placed in a paper bindle, put into a plastic bag, sealed with tape, put into a plastic bag, sealed with tape, labeledlabeled
Wet evidence Wet evidence - placed in a paper bag to - placed in a paper bag to allow drying, then treated like dry allow drying, then treated like dry evidenceevidence
When bag is sealed, person must sign When bag is sealed, person must sign their name across the sealtheir name across the seal
Making a Making a paper bindlepaper bindle
Fold the paper into thirds both Fold the paper into thirds both directions so you end up with 9 directions so you end up with 9 rectanglesrectangles
Place your evidence in the middle Place your evidence in the middle and fold paper around itand fold paper around it
Do you have any further questions Do you have any further questions on how to create a paper bindle?on how to create a paper bindle?
Chain of CustodyChain of Custody
Must be Must be attachedattached to evidence to evidence containercontainer
Starts with person who Starts with person who findsfinds evidence evidence The next person to use or analyze the The next person to use or analyze the
evidence must fill out a labelevidence must fill out a label Ensures evidence is handled Ensures evidence is handled
correctlycorrectly If it is not handled correctly, can be If it is not handled correctly, can be
traced to who’s responsibletraced to who’s responsible
Crime Scene ReconstructionCrime Scene Reconstruction
Crime scene reconstruction Crime scene reconstruction involves: involves: forming a hypothesis of the forming a hypothesis of the
sequence of events from before sequence of events from before the crime was committedthe crime was committed
BEWARE of staged crimes (cover BEWARE of staged crimes (cover ups)ups)
Staged Crime ScenesStaged Crime Scenes
When the lab results When the lab results do not match do not match up up with the testimony of witnesses, it can with the testimony of witnesses, it can mean the crime was mean the crime was stagedstaged
Common examples include: Common examples include:
Staging a fire—to cover bankruptcy. Staging a fire—to cover bankruptcy. Staging a suicide—to cover a murder. Staging a suicide—to cover a murder. Staging a burglary—to collect insurance Staging a burglary—to collect insurance
money.money.
Staged Crime Scenes (cont)Staged Crime Scenes (cont)
To help determine whether a crime To help determine whether a crime scene was staged, consider: scene was staged, consider:
Whether the Whether the type of wound found type of wound found on on the victim matches the weapon employed. the victim matches the weapon employed.
Whether the wound could have been Whether the wound could have been easilyeasily self-inflicted. self-inflicted.
The The mood and actions mood and actions of the victim of the victim before the event. before the event.
The The mood and actions mood and actions of a suspect of a suspect before the event.before the event.