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
what kind of containers are liquids and arson remain stored in
airtight, unbreakable containers
what kind of containers are hair, glass, fiber, and other kinds of trace evidence put in?
plastic pill bottles
why are bloodstained materials packaged in wrapping paper, manila envelops, or paper bag?
to prevent the growth of mold which can destroy the evidential value of the blood
charred debris from a fire must be sealed in an ?
airtight container
what 2 things must always be attached to the evidence container?
an evidence log and a chain of custody
what does the evidence log include?
description of evidence, name of suspect, name of victim, date and time of recovery, signature of person who is recovering the evidence, and signature of any witness present during collection
chain of custody
a list of all the people who came into possession of an item of evidence
true or false: control samples should always be taken from the victim for purposes of exclusion
true
standard/reference sample
physical evidence whose origin is known, such as blood or hair from a suspect that can be compare to crime scene evidence
when there is a bloodstained evidence. a whole blood sample ( withdrawn from a vein) or _____ swab must be obtained from all crime scene participants
buccal ( cheek )
to whom are lab results sent too?
the lead detective
true or false : evidence does not lie but it can be staged
true
what should be concidered when determining if a crime scene is staged?
- Initially treat all death investigations as homicides
- Do the type of wounds on the victim match the weapon?
- Could the wounds be easily self-inflicted?
- Establish a profile of the victim through interviews with friends and family.
- Evaluate the behavior (mood and actions) of the victim before the event.
- Evaluate the behavior (mood and actions) of any suspects before the event.
- Corroborate statements with evidential facts.
- Reconstruct the event.
any removal of evidence from a crime scene must be in accordance with the
4th amendment
true or false: do not investigate a scene or remove evidence without a warrant
true
in what circumstances can a crime scene be searched without a warrant?
i. under emergency circumstances (danger to life or limb)
ii. if there is immediate danger of the loss or destruction of evidence
iii. if there is probable cause — the search of a person and their immediate property in conjunction with a lawful arrest
iv. with the consent of the involved parties
mistaken eyewitness identifications contributed to approximately __% of the more than 360 wrongful convictions in the united states
71
what is a “double bind” procedure?
lineup is one in which neither the administrator nor the eyewitness knows who the suspect is
what is a “ sequential presentation of lineups”
when combined with a “blind” administrator, presenting lineup members one-by-one (sequentially), rather than all at once (simultaneously), has been proven to significantly increase the overall accuracy of eyewitness identifications
what is “ instructions”
are a series of statements issued by the lineup administrator to the eyewitness that deter the eyewitness from feeling compelled to make a selection. They also prevent the eyewitness from looking to the lineup administrator for feedback during the identification procedure. One of the recommended instructions includes the directive that the suspect may or may not be present in the lineup
composing the lineup
Suspect photographs should be selected that do not bring unreasonable attention to the suspect. Non-suspect photographs and/or live lineup members (fillers) should be selected so that the suspect does not stand out from among the other fillers. Law enforcement should select fillers using a blended approach that considers the fillers’ resemblance to the description provided by the eyewitness and their resemblance to the police suspect
confidence statments
Immediately following the lineup procedure, the eyewitness should provide a statement, in his own words, that articulates the level of confidence he or she has in the identification made
true or false: the lineup procedure should be documented
true
