Please enable JavaScript.
Coggle requires JavaScript to display documents.
Module 6: Evidence Handling Procedures - Coggle Diagram
Module 6: Evidence Handling Procedures
Physical Evidence
refers to a wide range of physical objects that are often minute in size
firearms and fired ammunition
fingerprints
toolmarks
tire tracks
footwear impressions
hair
fibers
glass
paint
trace
minute and transient, but measurable; often needs equipment like microscopes for examination
Physical evidence must be handled carefully to ensure its integrity and to make sure any test that needs to be completed on it can be, as some testing may be destructive
proper collection and preservation
adequate storage conditions
careful handling
may be corroborative (which can confirm or support the theory of a crime) or circumstantial (which indirectly infers a particular conclusion regarding the crime)
Biological Evidence
consists of bodily fluids and tissues that contains DNA that can be used for identification
blood
semen
saliva
bone
hair
skin
touch DNA - it's possible to obtain a DNA profile from an object someone has simply touched
because biological/DNA evidence is often so important, care must be taken to ensure it doesn't degrade or become contaminated
air dry as soon as possible
keep in paper packaging
wear proper PPE when handling
keep in dark, temperature-controlled storage (ideally)
Drug Evidence
consists of both legal and illegal substances controlled by law
medications
white powders
marijuana
clandestine labs
can come from many different situations
possession of controlled substances
cocaine
heroin
manufacture of controlled substances
methamphetamines
cultivation of plants
marijuana
opium poppy
possession of drug paraphernalia
pipes
syringes
can be dangerous to handle - may come into contact with bloodborne pathogens, caustic materials, and psychoactive compounds
Other Evidence Types
crime scene reconstruction
questioned documents
toxicology
computer crimes
Class & Individual Characteristics
Class Characteristics
Measurable features of an item that indicate a restricted group source based on design factors determined prior to manufacture
width of the tip of a screwdriver
bloodstains
Individual Characteristics
Marks on an object produced by the random imperfections or irregularities on the surfaces of the tools used to manufacture the object; can be produced on an object by general use, abuse, or corrosion
DNA profiles
striation marks on a fired bullet
Associative Evidence
evidence that originates from contact between people and objects; used to provide links between pieces of evidence and individuals
latent fingerpritns
fibers
semen
saliva
hair
soil
there are four factors in determining the value of associative evidence
Specificity or identity of the material
Frequency of occurrence of the measured attribute
Persistence, or how long the material is detectable after deposition
Likelihood of alternate explanations
Crime Scene
safety at the crime scene is always the first priority
the crime scene should be documented with written and audio notes as well as still and video photography
there are several approaches to examining a scene
spiral - starting at the perimeter of the scene and working your way inward
parallel - going in a straight line from one side to the other, then turning around to do a parallel line
grid - using the paralell method, then doing it again at 90 degrees to the first line
zones - using quadrants or larges areas to search
procedures in packaging a firearm or toolmark-related evidence
protection of the crime scene and evidence is also important, so limiting who can be there and wearing appropriate PPE is important
Evidence in the Laboratory
lab safety concerns
ensure that any firearm is properly unloaded so that it is safe for any handling that may need to be done
ensure that sharp objects are packaged properly for safe handling
evaluate the packaging of any substance that could be a biohazard or hazardous in any other way
chain of custody needs to be maintained and must include a unique identifier, and item description, the identity of the collector, the time and date of collection, and the location of collection
methods of case assignment
the person who is responsible for examining a piece of evidence becomes the hub of the chain of custody, is responsible for proper examination of sequencing, and should be aware of the possible implications of biological and trace evidence
centralized vs examiner-based systems
In a centralized system, a lab manager will break the seal of the container holding the evidence, determine the type of examination(s) that are needed, and coordinates the distribution of the piece of evidence with appropriate forensic examiners
An examiner- based system is similar to a centralized system, but differ in that the lab manager should identify any examinations that were not requested and need a familiarity with their lab and its capabilities