Fingerprinting Flashcards
What is individualized physical evidence?
Evidence that is unique and can be directly linked to a specific person and/or source e.g. fingerprints, DNA, bullet casings, dental impressions
What is identified physical evidence?
Evidence that shares a common source; it can be grouped into a class of items having similar properties e.g., clothing, shoe prints, blood type
Which of the two types of evidence is more valuable?
Individualized physical evidence is more valuable because it can be directly linked to a suspect.
When can identified physical evidence be useful?
When it directly supports individualized evidence and/or when it is presented with additional pieces of identified evidence.
Why did the jury convict Scott Peterson in the Laci Peterson case, even though only one piece of individualized evidence was presented?
Because when combined with the identified evidence from the prosecution, the strand of hair helped prove Peterson’s guilt.
Why did the defence in the Laci Peterson case argue that the strand of hair presented as individualized evidence was actually identified evidence?
Because the DNA from the hair was mitochondrial DNA (mtDNA) and they felt that mtDNA wasn’t as reliable as nuclear DNA.
Why is physical evidence important?
It is important because it can confirm the identity of the suspected individual.
Before fingerprinting was discovered, how did police classify criminals?
They used body measurements such as arm length, foot length, height and head circumference.
What are the three types of fingerprint evidence that can be left at a crime scene?
Visible, latent and physical.
What is a visible fingerprint?
Visible fingerprints are easily seen by the human eye. They may be left on an object at a crime scene because of blood, perspiration, dirt, or oils on a suspect”s hands.
What is a latent fingerprint?
Latent fingerprints are hidden or concealed in some way and are, therefore, not visible to the naked eye. Most latent fingerprints are composed of perspiration and/or body oils. These types of prints need to be enhanced in some way to be visible.
What is a physical fingerprint?
Physical fingerprints occur when distinct impressions are left upon soft materials such as wax, food items, or the caulking around windows and doors.
What causes fingerprints to be left behind?
Each ridge of the epidermis is dotted with sweat pores and is attached to the dermis. Sweat glands produce a water-based oil solution that is released from each sweat pore and coats the ridges of the epidermis. The ridges on the fingertips retain sweat and when the finger makes contact with a surface, sweat residue is left behind.
What is the epidermis?
The outer layer of the skin where the fingerprint ridges are found.
What is the dermis?
The inner layer of the skin where the sweat glands are contained.
What are the identifying qualities of fingerprint arches?
They are the rarest pattern (approx. 6% of people have it) and their ridges cross smoothly and raise towards the centre. Their sub-classes are plain/simple arch and tented arch.
What are the identifying qualities of fingerprint whorls?
Approximatly 34% of people have them and the ridges form circles, whirlpools or spiral shapes. Their sub-classes are simple/plain whorl, central pocket whorl, and accidental whorl.
