Crime Scene Crime Scene Investigation & Investigation &

Evidence CollectionEvidence Collection

Lessons from the JonBenet Lessons from the JonBenet Ramsey CaseRamsey Case

► In 1996, six year-old JonBenet Ramsey In 1996, six year-old JonBenet Ramsey was found murdered in the basement of was found murdered in the basement of her home.her home.

►This crime scene reveals how important it This crime scene reveals how important it is for crime scene investigators to secure is for crime scene investigators to secure a crime scene immediately or valuable a crime scene immediately or valuable information may be lost forever.information may be lost forever.

►To this day, the case remains unsolved.To this day, the case remains unsolved.

Goal of Crime Scene Goal of Crime Scene InvestigationInvestigation

►Recognize, document and collect Recognize, document and collect evidenceevidence

►The evidence collected at a crime The evidence collected at a crime scene is all investigators have to go on scene is all investigators have to go on to recreate a picture of what happened to recreate a picture of what happened at the scene.at the scene.

Principle of ExchangePrinciple of Exchange

► First described by Dr. Edmond Locard First described by Dr. Edmond Locard (sometimes called Locard’s Exchange Principle)(sometimes called Locard’s Exchange Principle)

► Defined as the physical transfer of materials Defined as the physical transfer of materials such as hair, fibers, blood, and skin cells when such as hair, fibers, blood, and skin cells when two people come in contact with each othertwo people come in contact with each other

► The longer (or more intense) the contact, the The longer (or more intense) the contact, the greater amount of trace evidencegreater amount of trace evidence

Types of Trace EvidenceTypes of Trace Evidence

►Animal or human hairAnimal or human hair►FingerprintsFingerprints►Soil or plant material (pollen)Soil or plant material (pollen)►Body fluids (mucus, semen, saliva, Body fluids (mucus, semen, saliva,

blood)blood)►Fiber or debris from clothingFiber or debris from clothing►Paint chips, broken glass, chemicals Paint chips, broken glass, chemicals

(drugs, explosives)(drugs, explosives)

Types of EvidenceTypes of Evidence

►Direct evidence – includes firsthand Direct evidence – includes firsthand observations, such as eyewitness accounts observations, such as eyewitness accounts or police dashboard video cameras and or police dashboard video cameras and confessionsconfessions

► Circumstantial evidence – indirect evidence Circumstantial evidence – indirect evidence that can be used to imply a fact, but does that can be used to imply a fact, but does not directly prove itnot directly prove it

- provides a link between a crime scene - provides a link between a crime scene and a suspectand a suspect

Circumstantial EvidenceCircumstantial Evidence

► Can be physical or biologicalCan be physical or biological

► Physical evidence– includes fiber, weapons, bullets, Physical evidence– includes fiber, weapons, bullets, and shell casingsand shell casings Reduces the number of suspects to a specific smaller Reduces the number of suspects to a specific smaller

group of individualsgroup of individuals

► Biological evidence – includes body fluids, hair, Biological evidence – includes body fluids, hair, plant parts, and natural fibersplant parts, and natural fibers Makes the group of suspects very small, or reduces it to a Makes the group of suspects very small, or reduces it to a

likely individuallikely individual More persuasive in courtMore persuasive in court

Class Evidence vs. Individual Class Evidence vs. Individual EvidenceEvidence

►Class evidence – narrows an identity to Class evidence – narrows an identity to a group of persons or things (ex.; a group of persons or things (ex.; blood type)blood type)

► Individual evidence – narrows an Individual evidence – narrows an identity to a single person or thing identity to a single person or thing (ex.; fingerprints)(ex.; fingerprints)

Crime Scene Investigative TeamCrime Scene Investigative Team

► Police officersPolice officers►District attorneyDistrict attorney► Crime scene investigators, including Crime scene investigators, including

recorders, sketch artists, photographers, recorders, sketch artists, photographers, evidence collectorsevidence collectors

►Medical examinersMedical examiners►DetectivesDetectives► Specialists (entymologist, forensic Specialists (entymologist, forensic

psychologist, toxicologist)psychologist, toxicologist)

Analysis of EvidenceAnalysis of Evidence

►Forensic labs process the evidence and Forensic labs process the evidence and send the results to the lead detectivesend the results to the lead detective

►Unlike CSI, lab techs are specialized Unlike CSI, lab techs are specialized and only process one type of evidenceand only process one type of evidence

►Test results lead to crime scene Test results lead to crime scene reconstructionreconstruction

Crime Scene ReconstructionCrime Scene Reconstruction

► Involves forming a hypothesis of the Involves forming a hypothesis of the sequence of events from before the sequence of events from before the crime was committed through its crime was committed through its commission.commission.

► Investigators look at evidence and Investigators look at evidence and attempt to determine how it fits into attempt to determine how it fits into the overall crime scenario.the overall crime scenario.

Staged Crime ScenesStaged Crime Scenes

►Create problems for investigators Create problems for investigators because the evidence does not match because the evidence does not match witness testimonywitness testimony

►Examples of staged crime scenesExamples of staged crime scenes ArsonArson Suicide/murderSuicide/murder burglaryburglary

Procedure to Use if Staged Procedure to Use if Staged Scene is SuspectedScene is Suspected

► Initially treat all deaths as homicidesInitially treat all deaths as homicides► Do the type of wounds match the weapon usedDo the type of wounds match the weapon used► Could the wounds be self-inflicted?Could the wounds be self-inflicted?► Establish a profile of the victim through family and Establish a profile of the victim through family and

friendsfriends► Evaluate behavior of victim prior to the eventEvaluate behavior of victim prior to the event► Evaluate behavior of suspects prior to the eventEvaluate behavior of suspects prior to the event► Corroborate statements with evidential factsCorroborate statements with evidential facts► Reconstruct the eventReconstruct the event► Conduct forensic examinations Conduct forensic examinations