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Forensics
CH 2 TEST
| Question | Answer |
|---|---|
| What is the goal of CRIME SCENE INVESTIGATION? | recognize DOCUMENTS & COLLECT evidence. Solving the crime depends on piecing together evidence & form a picture of what happened. |
| Dr. Edmund Locard believed that EVERY criminal can be connected to a crime by small particles carried from the scene. His PRINCIPLE STATES: | 1-Whenever 2 objects come into contact w/ one another a cross-transfer of physical evidence can occur. 2-The INTENSITY, DURATION & EXTENT in contact determine the EXTENT of the transfer. |
| Evidence can be CLASSIFIED in 2 TYPES: | 1-Direct Evidence =firsthand observations - EYE WITNESS account, VIDEOS, CONFESSIONS 2-CIRCUMSTANTIAL EVIDENCE -INDIRECT evidence used to IMPLY but doesn't directly prove it. ex. Finding someone's gun at the crime scene. |
| CIRCUMSTANTIAL EVIDENCE = divided into: | 1-Class Evidence: narrows evidence to a GROUP of persons or things. ex: BLOOD type narrows down suspects to a small group. 2-INIVIDUAL EVIDENCE: narrows evidence to a SINGLE person ex: fingerprints, handwriting, DNA, physical matches |
| Class Evidence narrows evidence to a _____ of persons or things. | GROUP |
| CLASS EVIDENCE | BLOOD type - this narrows down suspects to a small group |
| INIVIDUAL EVIDENCE | narrows evidence to a SINGLE person ex: fingerprints, handwriting, DNA, physical matches |
| CIRCUMSTANTIAL EVIDENCE | NDIRECT evidence used to IMPLY but doesn't directly prove it. ex. Finding someone's gun at the crime scene. |
| What is the goal of crime scene investigation | recognize, document, and collect evidence at the scene of a crime. Solving the crime will depend on piecing together the evidence to form a picture of what happened at the crime scene. |
| What's does Locard's Exchange Principle state | 1. Whenever 2 objects come in contact with one another, a cross-transfer of physical evidence can occur 2. The intensity, duration(time), and nature of the materials in contact determine the extent of the transfer |
| 2 types evidence can be classified | 1. Direct evidence 2. Circumstantial evidence |
| Define direct evidence | Firsthand observations (eyewitness account, videos, confessions) |
| Define circumstantial evidence | Indirect evidence can imply a fact doesn't prove it. Ex: finding a gun at a crime scene is circumstantial evidence that the suspect was there)The more circumstantial evidence there is, the greater weight it carries. (Probability and statistics) |
| Define physical evidence | Synthetic fibers, weapons, bullets, shell casings, paint chips, documents, imprints and prints (shoes, tires...), tool marks, soil, drugs, etc. |
| Define biological evidence | Body or body parts, body fluids, hair, leaves or other plant parts, natural fibers, feathers, wood |
| Define trace evidence | Small but measurable amounts of physical or biological material found at a crime scene. Examples: strand of hair, fingerprint, DNA, drop of blood, pollen, gunshot residue |
| What can evidence be divided into | 1. Class evidence 2. Individual evidence |
| Define class evidence | Narrows evidence to a group of persons Ex: blood type A, B, AB, O. Narrows down suspects to a smaller group Class evidence may become more individualized Ex: blue jeans. Narrow down by brand, material, size, color rips or stains to individualize them |
| Define individual evidence | Narrows evidence down to a single person or thing. Example: fingerprints, handwriting, DNA, and sometimes physical matches |
| What's the importance of evidence | Can prove, back up, link, determine the identity, allow investigators |
| 1. Importance of evidence: can prove | Can prove a crime has been committed and set the scene for the investigation Example: gasoline at the scene of a fire may prove arson |
| 2. Importance of Evidence: can back up | Can back up witness testimony or prove it false |
| 3. Importance of Evidence: can link | Can link a suspect with a victim or with a crime scene |
| 4. Importance of Evidence: can determine the identity | Can determine the identity of people associated with a crime |
| 5. Importance of Evidence: allows investigators | Allows investigators to reconstruct a crime Example: blood spatter may show where suspect and victim were in relation to one another and indicate what happened in what order |
| The Crime Scene Investigation Team | A group of professional investigators, each trained in a variety of special disciplines |
| Who's on the crime scene investigation team | 1. 1st police officer on the scene 2. Backup police/district attorney 3. Medics 4. Investigator/detective5. Medical examiner ( 6. Photographer and/or field evidence technician 7. Lab experts * must wear protective gear prevent contamination scene |
| Define district attorney | Elected or appointed official who represents the government in the prosecution of criminal offenses |
| What are the Seven S's of Crime Scene Investigation | 1. Securing the scene 2. Separating the witnesses 3. Scan the scene 4. See the scene 5. Sketching the scene 6. Search for evidence 7. Securing and collecting the evidence |
| 1. SECURING THE SCENE | The first responding police officer must make sure the scene is secure by first making sure all individuals in the area are SAFE and second by PRESERVING EVIDENCE |
| What should the first responding officer do | 1.Medical assistance 2. Arrests 3. Isolate area A. Exclude unauthorized personnel B. tape, ropes, barricades, guards-no one may enter/leave (keep a security log of all who visit scene) C. Prevent the loss of evidence 4. Request + needs officers, experts |
| 2. SEPARATING THE WITNESSES | 1. Witnesses must not be allowed to talk to one another. This prevents them from working together to create a story (collusion) |
| Define collusion | Witnesses working together to create a story |
| 2. SEPARATING THE WITNESSES | When questioning witnesses, the following should be asked 1. When did the crime occur?2. Who called in the crime? 3. Who is the victim? 4. Can the perpetrator be identified? 5. What did you see happen? 6. Where were you when you observed the crime? |
| The Innocence Project | 1. Created in 1992, goal was to re-examine post conviction cases |
| The Innocence Project | 2. evaluating eye witness testimony, investigator must decipher b/n fact and opinion. |
| The Innocence Project | What did the witness actually see? Ex. an innocent bystander running from a crime scene in fear of being shot could be mistaken for the shooter fleeing the crime. Witnesses must be examined to describe what they saw not what they thought |
| The Innocence Project | 3. Eyewitness misidentification is the single GREATEST cause of wrongful convictions nationwide, playing a role in nearly 75% of convictions overturned through DNA testing. |
| 3. SCAN THE SCENE | Forensic examiners scan the scene to see where photos should be taken. The primary and secondary crime scenes must be determined |
| The primary crime scene | is where a crime actually occurred. A secondary crime scene is in some way related to the crime but is not where the actual crime took place |
| 4. SEE THE SCENE | The Photography Unit takes photos of the overall area and close up photos with and without a measuring ruler |
| 5. SKETCHING THE SCENE | Accurate, drawn to scale a. NORTH should be labeled & a scale of distance b. All important objects (weapon and body) measured from 2 immovable landmarks c. objects in the vicinity of the crime included (Ex: doors, windows, furniture, trees, cars |
| 5. SKETCHING THE SCENE | d. Also include: DATE, TIME, LOCATION, CASE NUMBER, and NAMES (sketched by and verified by) 2. Later, a final copy (usually made on a computer) will be made for presentation in court |
| 6. SEARCH FOR EVIDENCE | 1. A SPIRAL, GRID, LINEAR or QUADRANT PATTERN should be walked and location of evidence marked, photographed and sketched. 2. A flashlight or black light may be used to help find trace evidence |
| 7. SECURING AND COLLECTING THE EVIDENCE | properly packaged, sealed and labeled using specific techniques and procedures |
| 7. SECURING AND COLLECTING THE EVIDENCE | 1. Metal or plastic forceps (tweezers) May have to be used to pick up small items |
| 7. SECURING AND COLLECTING THE EVIDENCE | 2. Plastic pill bottles with lids are preferred containers for hairs, glass, fibers, and other kinds of trace evidence |
| 7. SECURING AND COLLECTING THE EVIDENCE | 3.Liquids & arson remains stored airtight,unbreakable containers A. Bloodstained materials: packaged in paper,manila envelopes,or bags=prevent growth of mold =can destroy the evidential value of the blood.Air needs to flow = prevent moisture buildup. |
| 7. SECURING AND COLLECTING THE EVIDENCE | B. Charred debris from a fire must be sealed in an airtight container, such as new metal paint cans, to prevent any volatile petroleum residues from evaporating. This could be evidence of arson. |
| 7. SECURING AND COLLECTING THE EVIDENCE | 4.biological evidence stored in breathable containers so evidence can dry out, reducing the chances of mold contamination. After evidence has air dried, it's packaged into a paper bindle (or druggist's fold) then placed in a paper or plastic container. |
| 7. SECURING AND COLLECTING THE EVIDENCE | 5. The outer container sealed with tape and labeled with the signature of the collector written across the tape |
| 7. SECURING AND COLLECTING THE EVIDENCE | 6. An evidence log and a chain of custody must be attached to the evidence container |
| A. Includes description of evidence, name of suspect, name of victim, date and time of recovery, signature of person recovering the evidence, and signature of any witnesses present during collectionB. Chain of Custody- a list of all persons who came into |
Created by:
ssha13
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