Download presentation
Presentation is loading. Please wait.
Published byKelley Watts Modified over 8 years ago
1
The Crime Scene A look into evidence gathering and processing Mrs. Toth Some slides by Mrs. Ryan A look into evidence gathering and processing Mrs. Toth Some slides by Mrs. Ryan
2
Crime Scene Definition Crime Scene vs. Scene of the Crime Includes planning areas, flight paths, staging areas, surveillance Location of the actual crime
3
What is the Job Title? In the United States, crime scene investigators are usually called “criminalists” In the United Kingdom, crime scene investigators are usually called “scene of crime officers” In the United States, crime scene investigators are usually called “criminalists” In the United Kingdom, crime scene investigators are usually called “scene of crime officers”
4
What is the Job Title? Job titles in forensic fields vary widely from jurisdiction to jurisdiction Example: A crime scene analyst is a civilian employed by the police department in Las Vegas - allowed to carry guns - depending on the department, analysts can be civilian or law enforcement Job titles in forensic fields vary widely from jurisdiction to jurisdiction Example: A crime scene analyst is a civilian employed by the police department in Las Vegas - allowed to carry guns - depending on the department, analysts can be civilian or law enforcement
5
What is the Job Title? In Albany, 8 detectives make up a “support unit” that collects all areas of evidence instead of individual units
6
Lockard’s Theory: Review Dr. Edmund Locard’s theory for the exchange of evidence is widely recognized as the cornerstone of forensic science. Locard’s theory: Whenever two objects come into contact, a transfer of material will occur. Evidence that is transferred can be used to associate objects, individuals or locations. Dr. Edmund Locard’s theory for the exchange of evidence is widely recognized as the cornerstone of forensic science. Locard’s theory: Whenever two objects come into contact, a transfer of material will occur. Evidence that is transferred can be used to associate objects, individuals or locations.
7
VictimSuspectCrime Scene Through evidence, try to connect the: Lockard’s Theory: Review
8
Examples of trace evidence that is picked up or left behind: Hair, Fibers - From the individual, their spouse, child, pets, victim, etc. Every contact leaves a trace… Soil, sand, plant matter, sawdust - Picked up on a person’s shoes
9
Class versus Individualized Evidence Class evidence - evidence that can only be grouped into a general category; cannot be pinpointed to a direct person or object ex. Black Lab Hair Individualized evidence - evidence that can be pinpointed to only one individual or object; unique ex. Fido’s hair (a black Labrador) through DNA Class evidence - evidence that can only be grouped into a general category; cannot be pinpointed to a direct person or object ex. Black Lab Hair Individualized evidence - evidence that can be pinpointed to only one individual or object; unique ex. Fido’s hair (a black Labrador) through DNA
10
Class versus Individualized continued Trace Evidence Hair Dog Hair Black Labrador Retriever Hair DNA from hair individualized to Fido (a black Labrador Retriever) Class Individualized
11
A single piece of class evidence can rarely convict someone, though it may exclude a suspect. However sheer numbers of class evidence can make coincidence unlikely. A single piece of class evidence can rarely convict someone, though it may exclude a suspect. However sheer numbers of class evidence can make coincidence unlikely. Ex. Porco case Class versus Individualized continued
12
“Common Source” Not “Match” When two objects share a class identity For example, white tennis shoes –The “common source” can be the factory, owner, or even where found –Suspect owns white tennis shoes and one is left at crime scene; try to see if the CS shoe came from a “common source” as the one in his apartment Example, fibers on a body in ditch –Fibers on body belong to an automobile –Find a suspect, try to see if fibers in his car are from “common source” as the fibers on the body When two objects share a class identity For example, white tennis shoes –The “common source” can be the factory, owner, or even where found –Suspect owns white tennis shoes and one is left at crime scene; try to see if the CS shoe came from a “common source” as the one in his apartment Example, fibers on a body in ditch –Fibers on body belong to an automobile –Find a suspect, try to see if fibers in his car are from “common source” as the fibers on the body
13
Evidence Types Evidence Direct Circumstantial PhysicalBiological
14
Evidence Types 1.Direct Evidence: evidence that, if true, proves an alleged fact, such as eye witness account of a crime Ex. Police dashboard video cameras Witness testimony 1.Direct Evidence: evidence that, if true, proves an alleged fact, such as eye witness account of a crime Ex. Police dashboard video cameras Witness testimony
15
Evidence Types 2. Physical or Real evidence (A type of indirect evidence): A tangible object related to a crime. Ex. Bloody knife at crime scene 3. Testimonial evidence (A type of direct evidence): Verbal accounting of an incident by a witness, victim or suspect. Ex. Neighbor says they have seen Suspect A with a knife at their house 2. Physical or Real evidence (A type of indirect evidence): A tangible object related to a crime. Ex. Bloody knife at crime scene 3. Testimonial evidence (A type of direct evidence): Verbal accounting of an incident by a witness, victim or suspect. Ex. Neighbor says they have seen Suspect A with a knife at their house
16
Evidence Types cont. 4. Indirect or circumstantial: evidence that supports other evidence; implies or infers facts; secondary Ex. Suspect A has expert training in knife skills; victim was stabbed to death in a technical manner 4. Indirect or circumstantial: evidence that supports other evidence; implies or infers facts; secondary Ex. Suspect A has expert training in knife skills; victim was stabbed to death in a technical manner
17
Value of Evidence Physical evidence: Cannot lie, die, quit, forget ….etc.; very good evidence!!! Testimonial evidence: may change, be unreliable, be mistaken or source can become unavailable during the case; questionable and therefore not reliable!! Physical evidence: Cannot lie, die, quit, forget ….etc.; very good evidence!!! Testimonial evidence: may change, be unreliable, be mistaken or source can become unavailable during the case; questionable and therefore not reliable!!
18
Physical Evidence Issues Not recognized, identified or overlooked Not legally collected Not properly collected and/or packaged Not properly stored Not properly tested Chain of custody issues Not recognized, identified or overlooked Not legally collected Not properly collected and/or packaged Not properly stored Not properly tested Chain of custody issues Often…
19
Maintaining a Chain of Custody As evidence is collected, the evidence bag is initialed by the collector and dated Anyone who possess the evidence during the investigation must sign for it as a record Failure to document can have evidence excluded from case/trial As evidence is collected, the evidence bag is initialed by the collector and dated Anyone who possess the evidence during the investigation must sign for it as a record Failure to document can have evidence excluded from case/trial
20
Evidence Issues continued Most of the mistakes made in the collection, securing and testing of evidence can be attributed to the lack of training and understanding. Ex. OJ Simpson Case - mishandled evidencemishandled evidence
21
Jon Benet Ramsey A Forensic Nightmare
24
John and Patsy Ramsey Jon Benet’s parents
25
The “War and Peace” of Ransom Notes
26
The Ramsey House
27
Jon Benet’s neck at autopsy
28
The garrote made from a broken paintbrush
29
The Autopsy Report
30
Jon Benet’s Grave
31
Why have protocols? The errors made in the Jon Benet Ramsey case and in the Nicole Brown Simpson murder compromised the investigation Proper procedure and methods would have prevented these errors The errors made in the Jon Benet Ramsey case and in the Nicole Brown Simpson murder compromised the investigation Proper procedure and methods would have prevented these errors
32
Processing the Crime Scene Important to remember that crime labs DO NOT solve crimes Only investigations by police solve crimes Forensics merely helps the police to do their job Important to remember that crime labs DO NOT solve crimes Only investigations by police solve crimes Forensics merely helps the police to do their job
33
Processing the Crime Scene 1 st Officer’s responsibilities –Preserve and protect the area; mark off larger than needed –Call for back-up –Log all who come in/out; controls evidence tampering –The enter/exit area of the perpetrator is recorded as well –Police must ensure suspect can not return to the scene to destroy evidence 1 st Officer’s responsibilities –Preserve and protect the area; mark off larger than needed –Call for back-up –Log all who come in/out; controls evidence tampering –The enter/exit area of the perpetrator is recorded as well –Police must ensure suspect can not return to the scene to destroy evidence
34
Steps in Processing the Crime Scene 1.Provide medical assistance; save and preserve life
35
Saferstein video: Processing a crime sceneProcessing 2. Secure the scene Arrest/detain suspects Use crime scene tape, barricades, cars, officers Exclude ALL unnecessary people Initial walkthrough: -entry & exit? -overview of scene -any specialists needed? Keep hands in pockets! Steps in Processing the Crime Scene
36
3. Document the scene Steps in Processing the Crime Scene Limited time available to work a crime scene »Three methods of crime-scene recording: 1.Photography 2.Sketches 3.Notes Limited time available to work a crime scene »Three methods of crime-scene recording: 1.Photography 2.Sketches 3.Notes
37
Forensic Photographers Important: Scene must be unaltered - if changed, photos could be inadmissible as evidence Photos are taken of entire crime scene, including surrounding areas; enter and exit areas taken at various angles; adjacent rooms Bodies are also heavily photographed in relation to where they are in the scene Important: Scene must be unaltered - if changed, photos could be inadmissible as evidence Photos are taken of entire crime scene, including surrounding areas; enter and exit areas taken at various angles; adjacent rooms Bodies are also heavily photographed in relation to where they are in the scene
38
Forensic Photographers As physical evidence surfaces, they are photographed; often with something next to them to indicate size (ruler or measuring tape) Photographers are only able to begin taking photos once they have been given the okay from the crime scene manager As physical evidence surfaces, they are photographed; often with something next to them to indicate size (ruler or measuring tape) Photographers are only able to begin taking photos once they have been given the okay from the crime scene manager
39
Forensic Photographer Equipment: –35mm and digital cameras; corresponding film –Standard light (flash) –Colored filters, light beams, UV (stains/fingerprints after treated with superglue or DFO), violet (gunshot residue/blood), blue and green light (prints/fibers/urine/semen) Equipment: –35mm and digital cameras; corresponding film –Standard light (flash) –Colored filters, light beams, UV (stains/fingerprints after treated with superglue or DFO), violet (gunshot residue/blood), blue and green light (prints/fibers/urine/semen)
40
Forensic Photographer Key point about photography is that it allows the police to reopen a crime scene quickly, like a busy street - all evidence has been captured on film They must be ready 24/7 Extremely difficult job because reliant on this person’s experience to get all data Key point about photography is that it allows the police to reopen a crime scene quickly, like a busy street - all evidence has been captured on film They must be ready 24/7 Extremely difficult job because reliant on this person’s experience to get all data
43
Sketches After the photographer is finished, crime scene investigators make a rough sketch of scene Shows the location of all objects Objects are located from two fixed points in the room like walls or a doorknob; called DATUM All measurements are made with a tape measure After the photographer is finished, crime scene investigators make a rough sketch of scene Shows the location of all objects Objects are located from two fixed points in the room like walls or a doorknob; called DATUM All measurements are made with a tape measure
44
N Measure from two fixed points 3 ft 1 in 6 ft 3 in
45
Sketches Often use number or letter cards by evidence Finished or final sketch is completed back at the lab using computers and drafting materials –Looks “finished” –Has a legend instead of labels Often use number or letter cards by evidence Finished or final sketch is completed back at the lab using computers and drafting materials –Looks “finished” –Has a legend instead of labels
47
Notes Notes are continuously gathered at a crime scene Must identify the time evidence was found, location, description, who and how item was packaged Notes can also be taken using a tape recorder and by video; later must all be written down Notes are continuously gathered at a crime scene Must identify the time evidence was found, location, description, who and how item was packaged Notes can also be taken using a tape recorder and by video; later must all be written down
48
Steps to Processing the Crime Scene 4.Identify and interview witnesses - keep witnesses separated - don’t want stories contaminated 4.Identify and interview witnesses - keep witnesses separated - don’t want stories contaminated
49
5. Search the scene Be thorough and systematic by following a search pattern. ex. line, grid, spiral, quadrant (which one is chosen depends on locale & size of area and # of officers) Look for details… remember to look up too ! Be thorough and systematic by following a search pattern. ex. line, grid, spiral, quadrant (which one is chosen depends on locale & size of area and # of officers) Look for details… remember to look up too ! Read list of details to look for… Steps to Processing the Crime Scene
50
Systematic Search for Evidence A thorough, systematic search of the crime scene necessary for court Not necessarily done by forensic scientists There are four general search patterns 1) Spiral search 2) Grid method 3) Strip or line method 4) Quadrant or zone search A thorough, systematic search of the crime scene necessary for court Not necessarily done by forensic scientists There are four general search patterns 1) Spiral search 2) Grid method 3) Strip or line method 4) Quadrant or zone search
51
Systematic Search for Evidence Spiral Quadrant/ Zone Line/Strip Grid
52
Line Grid Quadrant Spiral Systematic Search for Evidence
53
6. Collect and package evidence Wear gloves, booties, mask, “bunny suit” while collecting Note: After 30 min. you can leave fingerprints behind through gloves ! Steps to Processing the Crime Scene
54
Label each item as follows: What is it ? eg. Blue fiber Where found ? Who collected it ? Collect and package evidence
55
Package each item separately and in proper packaging: Examples: - Hairs/ fibers: paper bindle or glassine envelope Collect and package evidence
56
Powders: plastic bags Collect and package evidence
57
Blood, semen stains: paper bags (prevents bacterial and fungal growth) *dry out first Collect and package evidence
58
Weapons, bullets, casings: cardboard boxes (prevents scratches) Collect and package evidence
59
Arson evidence: air tight, lined metal containers (prevents corrosion and evaporation of accelerants) Collect and package evidence
60
Paper documents: envelopes (paper or Tyvek) Collect and package evidence
61
Glass evidence: plastic vials (prevents scratches) Collect and package evidence
62
A hand-held vacuum with a special filter can be used to collect trace evidence Crime scene evidence is extended into the autopsy room: – victim’s clothing; fingernail scrapings; head and pubic hairs; blood; vaginal, anal and oral swabs; recovered bullets from the body; hand swabs from shooting victims A hand-held vacuum with a special filter can be used to collect trace evidence Crime scene evidence is extended into the autopsy room: – victim’s clothing; fingernail scrapings; head and pubic hairs; blood; vaginal, anal and oral swabs; recovered bullets from the body; hand swabs from shooting victims
63
Evidence Collection Kit
64
7. Maintain Chain of Custody Documentation of the movement of evidence from collection until case conclusion. Crucial to maintaining integrity of evidence. Steps to Processing the Crime Scene
66
The Top Ten Ways to Botch an Investigation Go to the listthe
Similar presentations
© 2024 SlidePlayer.com Inc.
All rights reserved.