Dactylography

Fingerprinting!

Dactylography

When was fingerprinting discovered?

• The first recorded use of fingerprints was in china roughly 3000 years ago

• They were used to authenticate an endorse documents

What are finger prints?• Every living person has a unique set of

fingerprints.• They are a complex pattern of ridges and

depressions on the tips of your fingers• They grow back, unless the damage is extreme• Your fingerprints develop at 5 months

gestation, and never change• You also have unique prints from other areas

of skin on your body –lip, foot, toe… etc.

Types of fingerprint patterns

Types of fingerprint patterns

• of people have loops– Radial (loop towards little finger side)– Ulna (loop towards thumb side)

• of people have whorls– Plain, double loop, accidental & central pocket loop

• of people have arches– Plain (smooth wave)– Tented (tapers to a point in the centre)

How are they created

• The grooves of your fingerprints contain glands that secrete sweat (salts & water), oils and amino acids.

• A little of this is left on every surface you touch

Types of fingerprints

• Patent (aka visible prints)– Visible to the naked eye– Produced when the finger has been in

contact with another substance (paint, blood, ink) then transferred onto a surface

– Do not require further processing

What sort of fingerprint?

Tented arch

What sort of fingerprint?

Radial loop

What sort of fingerprint?

arch

Fingerprint minutiae

Fingerprint minutiae

What sorts of minutiae?

Cross over

Ridge ending

bifurcation

bifurcation

Ridge ending

Pressure can change appearance

All primates have prints

Even Koalas have prints

Koala human

Collecting FingerprintsRight Side

Thumb Fore Finger Middle Finger

Ring Finger Little Finger

Left Side

Thumb Fore Finger Middle Finger

Ring Finger Little Finger

Pattern

Pattern

Collecting fingerprints1. Using a 2B pencil make a THICK layer of graphite in a small

rectangular area of your page.

2. Roll your finger around in the graphite till well coated

3. Cut a small section of sticky tape and press it to your finger (sticky side down)

4. Transfer the sticky tape print to the relevant box in your table

5. Complete the steps above for each finger

Collecting Fingerprints

• Identify the pattern of each print

• Identify any variations (circle in red pen)

Types of fingerprints

• Latent– invisible to the naked eye– requires additional processing to be seen.

can include basic powder techniques or the use of chemicals

Types of fingerprints

• Plastic– They are three-dimensional impressions – made by pressing your fingers in things

like fresh paint, wax, soap, or tar. – They are easily seen by the human eye

and do not require additional processing

Surfaces

• Non Porous materials are generally non absorbent and produce clear finger prints

• These materials consistent of things like: metallic objects, glass, ceramics, mirrors, plastics, painted or polished surfaces… etc

Surfaces

• Porous materials generally absorb body fluids, and are difficult (but not impossible) to collect fingerprints from

• These materials consistent of things like: fabrics, stone, raw timber, carpets…etc

Collecting Fingerprints

• There are two categories for methods of fingerprint collection.

• Manual– Dusting with powders

• Chemical– Coating/dusting with chemicals to cause a

chemical reaction (colour change)

Matching features of print• Level 1: the type of print• Level 2: :minutiae. These are the details in

a fingerprint. There are big details like starting lines, splitting lines and line fragments.

• Level 3: smaller details like pores, incipient ridges, and lineshapes.