Lesson 5 - Recording Friction Ridge Skin

3 Types of Exemplars

1. Fingerprint / Ten Print Card

2. Palm Print Card

3. Major Case Print Card / Complete Friction Ridge Exemplar

Ink & Paper

A way to acquire FRS exemplars - printer’s ink & roller, ink pad, fingerprint cards

Pros:

• Captures more of the finger

• Sharper detail

Cons:

• Too much or too little pressure

• Too much or not enough ink

• Movement / slippage

• Not fully rolled / recorded

• Overlapping or double touches

• Recordings of incorrect areas

Chemicals & Paper

A way to acquire FRS exemplars - inkless pads, chemically treated fingerprint cards

Pros:

• No mess

Cons:

• Old pads / chemicals can prevent proper recording

• Lack of “sharpness”

Livescan

A way to acquire FRS exemplars - electronic device

Pros:

• Fast & easy (plus easy to re-do if necessary)

• Lots of third level detail

Cons:

• Stitching errors / artifacts

• Blurriness

• Ghost impressions

• Poor quality

  • Too much or not enough residue

Accutrans / Mikrosil

A way to acquire FRS exemplars - 3D casting material

Pros:

• 3D recording of FRS

• Easy to use on dead bodies (rigor mortis)

Cons:

• Need to apply fingerprint powder first to get best detail

• Hard to photograph afterwards

Handi-Print

A way to acquire FRS exemplars - black fingerprint powder & white contact paper

Pros:

• Best way to get Major Case Prints

• Easy to use on dead bodies (rigor mortis)

Cons:

• Movement / Slippage

• Messy

Photography

A way to acquire FRS exemplars - camera & appropriate lens

Pros:

• No mess

• Can often get very good detail

Cons:

• Need to keep in mind that the ridges / furrows are flipped when comparing

Rolled Impressions

A fingerprint collected by rolling the finger from nail to nail

• Fingers are rolled outward

• Thumbs are rolled inward

Flat Impressions

aka Plain / Simultaneous / Slap

• A fingerprint collected by placing the finger straight down & then lifting straight back up

• The plain impressions are used to verify the sequence and accuracy of the rolled impressions

Writer’s Palm

aka the Hypothenar

• The area on the side of the palm that normally rests against the paper while writing

Major Case Print Cards

Recording of all FRS on hands…

• Distal, medial & proximal joints of fingers

  • Fully rolled

  • Left edge

  • Flat

  • Right edge

• Extreme fingertips

• Palm prints

  • Full palm

  • Writer’s palm

  • Thenar - this is not always recorded separately because it’s usually visible enough in the full palm

Decomposed (Putrefied) Skin

• Occurs due to bacteria, fungi & fermentation

• Usually fragile - take care when handling skin

• May need to remove FRS from underlying tissue

• Formaldehyde may be used to firm up skin

• Possible to print underside of skin or dermal skin = dermal papillae

Macerated Skin

• Occurs when friction ridge skin is immersed in water

• Epidermis separates from dermis = “de-gloving”

• May need to stretch the skin to remove wrinkles

• Can use tissue builder / glycerin

• Can wear de-gloved skin like a glove in order to get prints

• When the epidermis is missing the boiling technique can be used

Desiccated / Dry Skin

• “Mummified” or very old bodies that are past the beginning stages of decomposition & putrefaction

• May require use of a casting material = Accutrans or Mikrosil

• Usually requires removal of hands / feet

• Rehydration & softening

  • Sodium or potassium hydroxide

  • Dishwashing liquid or fabric softener

• Tissue builder / glycerin to “fill out” the skin

Charred Skin

• Subject to intense heat

  • Can draw fingers into tightly clenched fist - pugilistic attitude

  • Can cause separation of the epidermal layer

• Charring can cause the skin to be very brittle

• Refrigerate 5-7 days to allow epidermis to separate

  • May have to cut the connecting tissue

• Rinse frequently in clean warm water

The Boiling Method

aka Osmotic Rehydration

On a hand / foot that is missing the epidermis, the dermis can be re-hydrated enough to print by briefly (10-30 seconds) dipping the skin into boiling water.