Chapter 2 and 3 Powerpoint Flashcards
Recognition (scene)/ Examination (lab)
First Step
To know something because one has seen, heard, or experienced it before
Classification
Second Step
Placing things into groups according to their basic characteristics
The process of placing an object within a similar group of objects
Exclusion is just as important as inclusion
Exclusion
A demonstration that two objects do not have a connection, relationship, or association
Individualization
Third Step
demonstration that an item is unique, even among members of the same class, or that two separate objects were at one time a single object/had a common source or origin
Evaluation
Last Step
the process of putting together the evidence available with the objective of understanding the nature and sequence of events that created it
involves using physical evidence and the analyses on that evidence to understand the events that produced that same evidence
Reconstruction of a Homicide
Bloodstain pattern analysis
Patterns in area where body was found
Patterns in area where body was suspected to be moved from
Nature of the wounds on body
Other physical evidence left behind (casings, weapons, clothing)
Damage
Two or three dimension surfaces on evidence produced by tearing, cutting, breakage, and other processes
Cutting v tearing
Physical match
Deposits
material that is laid down or left behind by a physical process
NOT A DIRECT TRANSFER
Examples: dust on a dresser, blood pattern on floor or wall, cast off pattern on ceiling,pollen on vehicle
Imprints
two dimensional representation of an object left in some sort of medium when it has come into contact with a hard surface (blood, dust, paint, dirt)
Indentation
three dimensional representation of an object when it has been impressed into a soft receiving surface (sand, snow, mud)
Striations
result of a hard surface being marked by a hard object in motion along that surface
motion results in parallel/nearly parallel lines on the hard surface
toolmarks
Purpose of laws
Resolve disputes
enforce order
Probable cause
sufficient reason based on known facts to believe a crime has been committed or that certain property is connected with a crime
1929: Frye v United States
Use of polygraph to determine whether the defendant was being truthful
Court did not allow results
Test is not reliable
1993: Daubert v Merrell Dow Pharmaceuticals
Concerned with morning sickness drug that may have caused birth defects
Court issues guidelines for deciding the admissibility of scientific evidence in court
determines judge acts as gatekeeper when applying the criteria/guidelines for admitting the evidence
Daubert states that scientific tests must be:
subjected to significant testing
generally accepted (Frye Criterion)
Subjected to error rate analysis
Peer reviewed
Expert Witness
An individual whose training, knowledge, or experience, makes him/her a specialist in a subject and is deemed as qualified to give opinion testimony in a legal setting
Crime scene investigation includes:
processing and analysis
requires a systematic approach
Division of labor
Crime Scene: civilian vs. sworn
Laboratory Analysis
Investigations/Interviews/Interrogations/ Arrests
First responders
emergency medical personnel
patrol officers
fire department
Scene Security
establish a perimeter around the scene to keep unnecessary individuals (news reporters, public, other department personnel) from entering and contaminating the scene
Three levels of security
Outer perimeter: news reporters and public
Middle Perimeter: staging area for crime scene/detectives, etc.
Inner Perimeter: surrounds immediate area (should have officer with crime scene log posted here)
Preliminary Examination of the Scene
Initial Walk Through
What are the
- sights?
- smells?
- sounds?
- weather conditions
Types of documentation
photography
video
written notes
sketches
Types of photography
overall
mid range
close up
Overall photographs
show the scene as it is upon arrival
up and down street parking lot around building pictures from each directional point applies to area outside of building and inside building no focus on specific items
Mid Range Photographs
show spatial relationship and locations of items of evidence
at scene and with each other
Close up Photographs
Shows each item of evidence individually
with and without evidence marker
with and without scale
Video Documentation
With or without audio
follows photographs
SLOW
Sketch Documentation
Rough
Finished
Written Note Documentation
Write down all observations
Times and Measurements - Approximately
Personnel at scene
Four Common Search Patterns
Zone/Quadrant
Spiral
Line/Strip
Double Line/Strip
After all documentation is complete:
the evidence is collected
How to avoid contamination:
wear personal protection equipment
change ppe between collection and swabs
dont touch non evidence items
Evidence Packaging
consider the nature of the evidence
consider the fragility of the evidence
consider the probative value of the evidence
Questioned samples
samples from an unknown source
ex. fingerprint lifts
Known/Control Samples
samples taken from a known source
used for comparison purposes
Evidence labels should include:
case number item number description name and initials of personnel date collected
Evidence packaging must include:
evidence label
tape and heat seal
initials of personnel who sealed
may include chain of custody
Chain of Custody
Written record of possession of evidence
may be found on packaging, may be on property sheet, may be done electronically with barcodes
