Module 6: Evidence Handling Procedures

Physical Evidence

refers to a wide range of physical objects that are often minute in size

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

Biological Evidence

consists of bodily fluids and tissues that contains DNA that can be used for identification

because biological/DNA evidence is often so important, care must be taken to ensure it doesn't degrade or become contaminated

Drug Evidence

consists of both legal and illegal substances controlled by law

can come from many different situations

can be dangerous to handle - may come into contact with bloodborne pathogens, caustic materials, and psychoactive compounds

Other Evidence Types

Class & Individual Characteristics

Class Characteristics

Associative Evidence

evidence that originates from contact between people and objects; used to provide links between pieces of evidence and individuals

there are four factors in determining the value of associative evidence

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

procedures in packaging a firearm or toolmark-related evidence

Evidence in the Laboratory

lab safety concerns

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

firearms and fired ammunition

fingerprints

toolmarks

tire tracks

footwear impressions

hair

fibers

glass

paint

may be corroborative (which can confirm or support the theory of a crime) or circumstantial (which indirectly infers a particular conclusion regarding the crime)

trace

minute and transient, but measurable; often needs equipment like microscopes for examination

proper collection and preservation

adequate storage conditions

careful handling

blood

semen

saliva

bone

hair

skin

air dry as soon as possible

keep in paper packaging

wear proper PPE when handling

keep in dark, temperature-controlled storage (ideally)

touch DNA - it's possible to obtain a DNA profile from an object someone has simply touched

medications

white powders

marijuana

clandestine labs

possession of controlled substances

manufacture of controlled substances

cultivation of plants

possession of drug paraphernalia

marijuana

opium poppy

cocaine

heroin

methamphetamines

pipes

syringes

crime scene reconstruction

questioned documents

toxicology

computer crimes

Individual Characteristics

Measurable features of an item that indicate a restricted group source based on design factors determined prior to manufacture

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

width of the tip of a screwdriver

bloodstains

DNA profiles

striation marks on a fired bullet

latent fingerpritns

fibers

semen

saliva

hair

soil

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

protection of the crime scene and evidence is also important, so limiting who can be there and wearing appropriate PPE is important

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

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

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