The Crime Scene

Locard’s Principle Dr. Edmond Locard Dr. Edmond Locard Director of the world’s first forensic lab in France Director of the world’s first forensic lab in France Came up with the idea that when a person comes into contact with an object or another person, a cross-transfer of physical evidence can occur. Came up with the idea that when a person comes into contact with an object or another person, a cross-transfer of physical evidence can occur.

2 Main Types of Evidence Direct Direct Circumstantial Circumstantial

Evidence Direct evidence Direct evidence Circumstantial evidence Circumstantial evidence Trace evidence Trace evidence Class evidence Class evidence Individual evidence Individual evidence

Direct Evidence Consists of firsthand observations Consists of firsthand observations In court, this evidence involves testimony by a witness about what that witness personally saw, heard, or did. In court, this evidence involves testimony by a witness about what that witness personally saw, heard, or did. Examples: Examples: Eyewitness accounts Eyewitness accounts Police dashboard video Police dashboard video Confessions Confessions

Circumstantial Evidence Indirect evidence that can be used to imply fact but does not directly prove it Indirect evidence that can be used to imply fact but does not directly prove it May provide a link between a crime scene and a suspect May provide a link between a crime scene and a suspect Only suspect and victim actually see it left at crime scene Only suspect and victim actually see it left at crime scene Can be physical or biological Can be physical or biological

Circumstantial Evidence Examples: Finding a suspect’s gun at the site of a shooting Finding a suspect’s gun at the site of a shooting Biological evidence: Biological evidence: Body fluids, hair, plant parts, and natural fibers Body fluids, hair, plant parts, and natural fibers Physical evidence: Physical evidence: Fingerprints, footprints, shoe impressions, tire impressions, bullets, and tool marks Fingerprints, footprints, shoe impressions, tire impressions, bullets, and tool marks

Trace Evidence Type of Circumstantial evidence Type of Circumstantial evidence Physical transfer of material Physical transfer of material Examples: Examples: Hair Hair Fingerprints Fingerprints Soil Soil Blood Blood Kleenex Kleenex Fiber Fiber Glass Glass Paint chips Paint chips

Class Evidence Narrows an identity to a group of persons or things Narrows an identity to a group of persons or things Cannot specify a single person Cannot specify a single person Only excludes people that do not fit the category Only excludes people that do not fit the category Examples: Examples: Blood types Blood types Hair color Hair color Common fibers Common fibers Shoe prints Shoe prints

Individual Evidence Narrows identity to a single person or thing Narrows identity to a single person or thing Examples: Examples: DNA DNA Complete fingerprints(not partials) Complete fingerprints(not partials) Tool marks Tool marks Anything torn or broken and left at the scene Anything torn or broken and left at the scene

5 S’s of Crime Scene Investigation Securing the scene Securing the scene Separating the witnesses Separating the witnesses Scanning the scene Scanning the scene Sketching and photograph the scene Sketching and photograph the scene Searching and collecting of evidence Searching and collecting of evidence

Securing the Scene The most important job at a crime scene The most important job at a crime scene Performed by the first officer at the scene, called the first responder Performed by the first officer at the scene, called the first responder Safety of all individuals in first priority Safety of all individuals in first priority Preservation of evidence is second Preservation of evidence is second Finally record the scene Finally record the scene

Separate the witnesses Separation prevents them talking to each other Separation prevents them talking to each other Each witness will be asked about the crime scene and what they observed Each witness will be asked about the crime scene and what they observed

Scan the Scene Determine if and where photos should be taken Determine if and where photos should be taken Determine if there may be a secondary crime scene Determine if there may be a secondary 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)

Sketching the Scene First is a Rough Sketch done at the scene First is a Rough Sketch done at the scene Must be accurate and to scale Must be accurate and to scale Note body, evidence, doorways, windows, walls, trees, cars, and movable objects Note body, evidence, doorways, windows, walls, trees, cars, and movable objects Distances should be measured and recorded Distances should be measured and recorded Case number, date, location, and time should also appear on the sketch Case number, date, location, and time should also appear on the sketch

Rough Sketch

Final Sketch Usually done by a computer Usually done by a computer Presented in court Presented in court

Photographing the Crime Scene Photograph: Photograph: All evidence All evidence Doors and windows Doors and windows Anything out of the ordinary Anything out of the ordinary

Searching and Collecting Evidence Must be properly packaged, sealed, and labeled Must be properly packaged, sealed, and labeled Dry evidence - placed in a paper bindle, put into a plastic bag, sealed with tape, labeled Dry evidence - placed in a paper bindle, put into a plastic bag, sealed with tape, labeled Wet evidence - placed in a paper bag to allow drying, then treated like dry evidence Wet evidence - placed in a paper bag to allow drying, then treated like dry evidence When bag is sealed, person must sign their name across the seal When bag is sealed, person must sign their name across the seal

Making a paper bindle Fold the paper into thirds both directions so you end up with 9 rectangles Fold the paper into thirds both directions so you end up with 9 rectangles Place your evidence in the middle and fold paper around it Place your evidence in the middle and fold paper around it

Collecting Evidence Evidence Label Evidence Label

Chain of Custody Must be attached to evidence container Must be attached to evidence container Starts with person who finds evidence Starts with person who finds evidence The next person to use or analyze the evidence must fill out a label The next person to use or analyze the evidence must fill out a label Ensures evidence is handled correctly Ensures evidence is handled correctly If it is not handled correctly, can be traced to who’s responsible If it is not handled correctly, can be traced to who’s responsible

Crime Scene Reconstruction Crime scene reconstruction involves: forming a hypothesis forming a hypothesis of the sequence of events of the sequence of events from before the crime was committed from before the crime was committed BEWARE of staged crimes (cover ups) BEWARE of staged crimes (cover ups)

Staged Crime Scenes When the lab results do not match up with the testimony of witnesses, it can mean the crime was staged; common examples include:  Staging a fire—to cover bankruptcy.  Staging a suicide—to cover a murder.  Staging a burglary—to collect insurance money.

Staged Crime Scenes To help determine whether a crime scene was staged, consider: Whether the type of wound found on the victim matches the weapon employed. Whether the type of wound found on the victim matches the weapon employed. Whether the wound could have been easily self- inflicted. Whether the wound could have been easily self- inflicted. The mood and actions of the victim before the event. The mood and actions of the victim before the event. The mood and actions of a suspect before the event. The mood and actions of a suspect before the event.