Unit 3-Physical Evidence Flashcards
Physical Evidence
Tangible objects, including weapons, and trace evidence. Real direct evidence to the crime.
Documentary Evidence
Any type of written or recorded evidence.
Demonstrative Evidence
Evidence that is used to help recreate a crime (for a trial)
Testimony
Evidence given by witness during a trial.
Identification
The process of determining the chemical/physical characteristics of a piece of evidence with as much certainty as possible.
Comparison
The process of testing a suspect sample with a known sample to prove whether or not they share a common origin.
Probability
The frequency of an event. How likely it is that 2 sources would share the same characteristics.
To test probability, what are the 3 things the test must be?
Reliable, Sensitive, and Specific.
Individual characteristics
Properties associated with a common source to a high degree of certainty.
Ridge Characteristic/ Minutiae
The ridge endings, enclosures, and other details that make up a fingerprint.
Class Characteristics
Can only be associated with a group and not a single source.
Physical properties
Described a substance/object without referring to another substance (weight,volume,size,colour)
Chemical properties
Describes what happens when a substance reacts with another substance.
What is used to help characterize a piece of glass at a crime scene?
Density and refractive index. Will vary in a single sheet of glass.
Radial fracture
Fractures that extend out words like spokes on a wheel.
Concentric Fractures
Fractures that form a circle around the point of impact.
What is the order in which fractures happen?
Radial Fracture, then concentric fracture.
Soil
A surface material from the earth.
How are soil samples collected?
Within a 100-yard radius of the crime scene in various locations, only take surface materials, about 1-2 tablespoons.
How are soil samples/ objects with soil preserved?
They’re preserved so that any dirt that falls off is retained.
What cast filling was discontinued?
Plaster of Paris, crumbled too easily
When finding an impression in dust or rough surfaces use what?
An electrostatic dust print lifter.
What do you use to remove an impression found on smooth surfaces?
Clear tape to lift it.
Do forensic scientists need extra training to do soil analysis?
Yes!!!
Can soil be compared by colour and texture?
Yes!!!!
