Test #1 Flashcards
Forensic Science vs. Forensic Identification
1) - natural and physical sciences - theory based - bench scientists 2) - applied science - based on scientific methodology, but investigative based
CSI vs. FIS
1)
- crime solved in 60 mins
- tests always work and result in a match
- suspects often plant false evidence
- exotic locations with great vehicles
- the do it ALL
2)
- crime is never solved in 60 mins
- tests often prove negative
- false leads are few and usually easily spotted
- bug infected rooming houses
- require physical match
- we enjoy our work
What is a fingerprint?
An impression left on a surface by the friction ridges of the skin on your fingers
What is a live scan?
10 rolled fingerprints taken from criminals
What materials are fingerprints often found in?
Sweat, dirt, blood, paint, etc.
What is ridgeology?
The study of uniqueness of friction ridge structures and their use for personal identification
Where can friction ridges be found?
Fingers, palms, and soles
Does dermal papillae change throughout life?
No
Dermis vs. Epidermis
1) Thick foundation
2) Thin outer layer
- attached by double row of dermal papillae
What is a familial tendency?
Similarity of pattern sequence but never the same
What are the 4 premises?
1) the form during fetal development
2) they don’t change
3) they are unique
4) they are classifiable resulting in searchable database
What was used before fingerprinting?
Anthropometric measurements
What are the 3 basic patterns?
1) Arch
2) Loop
3) Whorl
What are the relationships between fingerprint pattern, and volar pad tension & pressure?
1) High-centred Pads = Whorl = High Pressure
2) Med-centred Pads = Loop = Med Pressure
3) Low-centred Pads = Arch = Low Pressure
What are the 3 levels of fingerprint analysis?
1st) Pattern
2nd) Minutiae
3rd) Ridge edges and pores
What are 3 anomalies used to identify fingerprints?
1) Ridge ending
2) Bifurcation
3) Ridge dots
Do interdigital or hypothenar and thenar pads form first?
Interdigital pads for first
What happens at 6 weeks (Volar pads)?
Volar pad starts forming on palm
When do volar pads start to regress on the palm and fingers?
1) 10 weeks
2) 11 weeks
What happens at 8 weeks (Volar pads)?
Fingers separate and volar pads form on the fingers
What happens at 10 weeks (Volar pads)?
Digital pads are distinct
What happens at 12 weeks (volar pads)?
Friction ridges start to develop in the basal layer, and volar pads regress
A ridge is referred to as a _______?
A furrow is referred to as a _______?
1) Hill
2) Valley
Why do we have friction ridge skin?
To improve grip and prevent slippage
What does each ridge have and why?
Single row of pores, used as openings for sweat gland ducts
Will damage to the epidermis have an effect on the fingerprint pattern?
No, but damage to the dermis will
What happens in weeks 5-7 for development of friction ridge skin?
- Fingers elongate
- Cartilaginous bones form
What happens in weeks 7-11 for the development friction ridge skin?
- Volar pads form
- Major creases form
What happens in weeks 11-17 for the development friction ridge skin?
- Volar pads regress
- Primary ridges form
- Sweat glands, ducts, and pores form
What happens in weeks 17-24 for the development friction ridge skin?
- Primary ridge development stops
- Secondary ridges form between primary ridges
What happens in weeks 24-27 for the development friction ridge skin?
- Friction ridges are fully developed in their final arrangement
- Dermal papillae form
- Basement membrane joins epidermis to dermis
Who developed the fingerprint classification system?
Sir Edward Henry
What are the 4 focal points for fingerprint identification at the 1st level?
Cores, Deltas, Scars, Creases
What did Sir Francis Galton propose?
Using fingerprints as a means of identifying criminals
What are the 4 individual ridge path/events used for identification at the 2nd level?
Ending ridges, Bifurcations, Dots, Islands
What are the 4 ways of identification using size and shape of pores and ridges at the 3rd level?
Pore sizes, End shapes and angles, Edge shapes, Width of ridge
What does forensics mean in latin?
Relating to or dealing with application
Who developed the 1st level of detail, and what is identifiable? What instrument is used?
- Henry
- Ridge flow and pattern, Core, Delta
- Visible to naked eye
Who developed the 2nd level of detail, and what is identifiable? What instrument is used?
- Galton
- Ridge endings, Bifurcations, Islands, Lakes, Dots
- Magnifying glass
Who developed the 3rd level of detail, and what is identifiable? What instrument is used?
- Ashbaugh
- Location of pores in the ridges, shapes of the edges of the ridges, how ridges effect each other
- Microscope
What are the five basic characteristics that combine to produce ridge patterns?
- Ridge Ending
- Bifurcation
- Ridge Dot
- Short Ridge (Island)
- Enclosure (Lake)
What are fingerprint secretions composed of?
Sweat, Sebum, Lipids, and/or Foreign materials picked up by the hands
What are the 3 sources of natural secretions on the human body?
- Eccrine sweat glands
- Sebaceous sweat glands
- Apocrine sweat glands
What is eccrine sweat composed of?
- 98.5% to 99.5% water
- 0.5% to 1.5% solids
What is sebum?
Secreted by sebaceous glands, found in areas covered by hair
What does sebum consist of?
Saturated fats, waxes and squalene, which makes it have a high affinity to fingerprint powders
What are the 5 factors affecting fingerprint secretions and concentration?
- Rate and duration of sweating
- Dietary habits
- Age
- Gender
- Stress
What 3 factors affect the life-span of a fingerprint?
- The person (genetic factors)
- The surface
- The environment
How can you tell the age of a fingerprint?
There is no accurate way of determining, unless there is something to corroborate it
- Time/dated receipt, newspaper, video surveillance, eyewitness account, etc.
What is a latent fingerprint?
A print that is invisible to the naked eye, that is caused by transfer of body perspiration or oils present on finder ridges to the surfaces of an object
What is a patent fingerprint?
Composed of secretions and foreign materials (ie. Blood, Grease, Dirt etc.) and transferred from the finger to the surface. Visible to the naked eye, they require minimal development and must be photographed
What it a plastic or mold impression?
3D impression in soft material:
- Chocolate
- Cheese
- Putty