FSC303: Fingerprinting

Ridgeology

the study of the uniqueness of the friction ridge structure and their use for personal identification

Sir william Herschel

• promoted fingerprinting use to prevent fruad and impresonation of contracts

• First european to recognize the value of friction ridge and their use for identification purposes.

Dr. Henery faulds

• Commented about locating fingerprints at crime scene and using them to apprehend the criminals responsible

• first to use fingerprints in criminal cases

Alphonse Bertillon

• Anthropometry - study of the measurements of the human body

• Personal identification through a series of body measurements

• Full face and profile photographs of perpetrator now commonly known as “mugshots” in criminal cases

Sir Francis Galton

• Galton details

• Responsible for the acceptance of the use of fingerprinting for personal identification

Troup committee

looked into:

1. the Bertillon system

2. Galtons fingerprinting identification method

and decided to use both since fingerprinting did not yet have an adequate system

Sir edward henry

Created a fingerprinting personal identification system in response to the Troup committee

Belper Committee

Revisted the registering and identifying of criminals in england, and recommended that all criminals records be classifies by henry’s classification system and made fingerprinting became a standard

Hands and Volar pad format

• at 6 weeks - hands is like paddle-like shape and volar pads can be seen

• at 8 weeks - Fingers seperate

• at 10 weeks - digital pads are distinct

• 12 weeks - friction ridges start to develop in basal layer and volar pads start to regress

Formation of Ridges

• they follow the curvature lines of the skin on the volar pads

• they develop all different speeds

Regression of Volar pads

• first flexion crease, apex, tip of the finger

Whorl

• high + narrow volar pad

• has at least one ridge in the middle making a complete circuit (spiral, oval, or circle)

• 30% of population

• one core, 2 delta

Arch

• Low + broad volar pad

• ridge enters through one side and exists through the other.

• No core or delta

• 5% of population

Ulnar loop

• Intermediate volar pad with steep radial slide

• The ridges enter from one side and re-curve and exist out the same direction

• flow of ridges exist towards the little finger

• 1 core, 1 delta

• 65%

Radial loop

• Intermediate volar pad with steep ulnar slide

• The ridges enter from one side and re-curve and exist out the same direction

• flow of ridge exist towards the thumb

• 1 core, 1 delta

• 65%

Friction Ridge characteristics

• Assist in ability to hold things

• provides traction to mitigate slippage

• Abundance of nerves

• Waste elimination through sweat glands

• Thick with layers to withstand daily functions

• no hair

• lack of pigmentation

• Each individual ridge unit has one sweat gland and one pore.

Dermis

• thick foundation layer 15-40x thick

Epidermis

• thin outer layer, 15-20 layers of dead cells that are shed and replaced by regeneration

• Stratum Corneum (top), Stratum Lucidum, Stratum granulusom, Stratum spinosum, Stratum basale (newest)

Basal layer

• Generating layer

• cells created flatten as the migrate to the top

• regeneration cycle initiated here usually takes 30 days to complete

Desmosomes

• connects the cells to one another

• they release and attach as needed during migration

• Surface cells are shed continuously as their junction points break down and there is always a new cell to replace

Injury or Disease of finger

• An injury that damges or penetrates the basal layer may detroy its ability to regenrate cells in that dmages area

• surrounding cells can regenerate, but the deformation will result in a scar on the surface

• Dysplia - normal cells undergoing abnormal changes

2nd level details

• ridge ending

• Bifuraction (splits)

• dot

• Island

• lake

• Identification and exclusion decisions can be made

3rd level details

• size & shape of pores, ridges

• ridge width

• adjacent ridge formation

• identification and exclusion decisions can be supported

1st level details

• whorl, arch, Loop (ulnar, radial)

enough prints

Continuous agreement of friction ridges, in sequence having sufficient uniquness to individualize

Finger deposit

1. Natural secretions

   1. Eccrine glands

   2. sabeceous glands

2. Foreign materials

Ecrine Glands

• found all over the body but in great amounts on hands and feet

• controlled by autonomic nervous system and respond to thermal, emotional or medical stimuli

• Composition: 98.5-99.5% water, 1.5-0.5% solids

Sabaceous Glands

• secretions are mainly saturated fats, waxes, and squalene

• Not naturally occurring on hands but end up there via migration process

Foreign materials

• any substance that is not created in the body

• paint, dust, dirt, blood

factors that impact Finger secretions

1. rate and duration of sweating

• excessive and prolonged sweating can dilute the concentration of solids within the sweat

2. Dietary habits

• certain food intake and lack can influence secretion content

3. age

• concentrations of components within sweat tends to lessen as we get older

4. physical health & fitness

may influence the quantity of sweat

5. stress level

• increases concentrations of solid in sweat, and rate.

Life span of print

how long can a fingerprint last on a surface

• there is no way to gauge this rn

• depends on; composition of the impression, the surface, the environment

Age of fingerprint

How old is the fingerprint. When was it deposited?

• can be determined through: Witnesses, CCTV and recordings, point of sales receipt - time stamped

Freezing temperature

This weather condition will solidify the secretions, and powder sticks to the background and print equally so no visible differences

Hot sunny weather

this weather condition causes the secretions to bake onto the surface as the moisture is quickly evaporated

High humidity

This weather conditions, is opposite to where powder sticking to everything and tends to smear the fingerprint impression and results in contaminating your brush

Surface suitability

Rule: Fingerprints can be found on any surface with sufficient size & surface continuity to disclose the necessary ridge characteristics in sequence. considers

• size

  • the possibililty of finding prints on small objects should not be ignores

• surface continuity

  • smoothness of an object is a limiting factor in disclosing ridge detail

• Material of surface

  • dictates what development technique is used

• Surface cleanliness

  • weigh pros and cons of brush contamination or take away

Deposit Impressions

• Majority of impression

• Transfer of material from friction ridges to the surface of an item

• print is latent if deposit if bodily secretions

• print is patent if deposit is foreign material

Latent impression

• cannot be easily seen under normal circumstances

• requires development techniques to be visible

• oblique lighting can reveal them before development

Patent impression

• Visible under normal circumstances and do not require enhancement

• photographed as is

• sometimes they are 2d and made up of foreign materials

take away impressions

when friction ridge removes material from a surface

plastic or mold impression

3D, typically only photographed, may be preserved with a casting material

Collecting a fingerprint

1. develop/locate - powder the surface and circle the impression with china markers

2. label - write all related information and place scale

3. photograph

4. document

5. Preserve: lift the impresion

Granular powders

• most widely used powders

  • easily transferable

  • easily airborn and can be messy to work with

  • works on a variety of non-porous surfaces

  • must be careful with overpowdering

  • used with fibre glass brush

• can be contaminated by moisture/foreign materials

Fibre Glass brush

• does least amount of damage to the impression and carries the most amount of powder

• Can cover most of surface before the need to recharge

• made up of nylon fibres

Magnetic powder

• contains iron particles and granular powder

• magnetic particles carrry the powder

• should not be used on magnetised surfaces

• applie with a magnetic wand - only the powder touches the surface

• mag powder eventually loses it effectiveness

Labelling Fingerprint impression

• circle with china marker and include R# and directionality arrow if necessary

• label include

  • Go#

  • date

  • location

  • badge

  • R#

Photographing a print

1. overall print - showing item in the scene

2. midrange - showing the print in relation to the item

3. close up - macro, (105mm, f16 or higher, ISO 100), fill the frame

4 premises of Friction ridges

1. Friction ridges develop on the fetus in their definitive form prior to birth

2. Friction ridges are persistent throughout life except for scarring, disease, or decomposition after death

3. Friction ridge paths and the details in the small area of the friction ridge are unique and never repeated

4. Friction ridge pattern vary within limits therefore allowing for classification