crime scenes Flashcards
chapter 1
what is the goal of a crime scene inventigation
to recognize, document, and collect evidence at the scene of a crime
what is locard’s exchange principle ( list both)
i.Whenever two objects come in contact with one another, a cross-transfer of physical evidence can occur
ii.The intensity, duration, and nature of the materials in contact determine the extent of the transfer
what is direct evidence (list examples)
firsthand observations (eyewitness account, videos, confessions )
what is circumstantial evidence ( list examples)
indirect evidence that can be used to imply a fact but does not directly prove it. Example: finding a suspect’s gun at a crime scene is circumstantial evidence that the suspect was there.
what are the 3 different types of circumstantial evidence
physical, biological and trace
what is physical evidence ( list examples)
synthetic fibers, weapons, bullets, shell casings, paint chips, documents, imprints and prints (shoes, tires, etc.), toolmarks, soil, drugs, etc.
what is biological evidence ( list examples)
body or body parts, body fluids, hair, leaves or other plant parts, natural fibers, feathers, wood
what is trace evidence ( list examples)
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
evidence can also be divided into..
class and individual
what is class evidence ( list examples)
narrows evidence to a group of persons or things
example: blood Type- can be A, B, AB, O. Finding one type at a crime scene narrows down the suspects to a smaller group
what is individual evidence ( list examples)
narrows evidence down to a single person or thing
example: fingerprints, handwriting, DNA, and sometimes physical matches
the crime scene investigation team
a group of professional investigators, each trained in a variety of special disciplines
what is a district attorney
elected or appointed official who represents the government in the prosecution of criminal offenses
true or false: it is not necessary for all people to wear protective gear at the crime scene
false. ALL people must wear protective gear to prevent contamination of the crime scene
what does the first responding police officer do upon entering the crime scene
must make sure the scene is secure by first making sure all individuals in the area are safe and second by preserving evidence
true or false: witnesses are allowed to talk to eachother
false, it prevent them from working together to create a story
when questioning the witness, what questions should be asked?
- When did the crime occur?
- Who called in the crime?
- Who is the victim?
- Can the perpetrator be identified?
- What did you see happen?
- where were you when you observed the crime?
what was the goal of the innocence project?
was to reexamine post conviction cases
what is the greatest cause of wrongful convictions nationwide playing a role in nearly 75% of convictions to be overturned through DNA testing
eyewitness misidentifications
what unit takes photos of the overall area and close up photos with and without a measuring ruler?
photography unit
what main things should always be on an accurate rough sketch of the crime scene that is drawn to scale
- north should always be labeled
- scale of distance
- all important objects ( body and weapon) should be measured from 2 immovable landmarks
a ____, _____,_____ or _____ ______ should always be walked and location of evidence marked, photographed and sketched
spiral, grid, linear, or quadrant pattern
true or false: a flashlight or blacklight may be used to help find trace evidence
true
what can be used to pick up small items
metal or plastic forceps