Fingerprinting

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ASISTM ProjectForensic Investigations

• Fingerprinting

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What are fingerprints?

• On the fingers and palms of the hands and the
  toes and soles of the feet the skin is covered
  with friction ridges.

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Photograph Paul Ricketts, 2006
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Why do we have friction ridges?

• Friction ridges are used to increase grip and the
  sense of touch.

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Photograph Paul Ricketts, 2006
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Friction ridges on the feet
Photograph Paul Ricketts, 2006
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Friction Ridge Patterns

• There are 3 main friction ridge patterns
• Loops - most common
• Whorls
• Arches - least common

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Loop
Image courtesy J. Dook, 2006
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Whorl
Image courtesy R. Henderson, 2006
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Arch
Image courtesy J. Dook, 2006
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Minutiae - fine detail
Image courtesy R. Henderson, 2006
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Minutiae Patterns
Image courtesy J. Dook, 2006
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Example
Image courtesy J. Dook, 2006
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Sweat Pores

• It is possible to see small white dots on the
  friction ridges - the white dots are sweat pores.

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Sweat pores
Image courtesy C. Henderson, 2006
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Identical Fingerprints?

• No two fingers have ever been found to possess
  completely identical friction ridge patterns.

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Twins
CH Left middle finger
RH Left middle finger
The boys both have a LOOP pattern but one of the
twins appears to have cut his finger at some
stage.
Image courtesy R. Henderson C. Henderson, 2006
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Twins Fingerprints

• The minutiae or fine details of identical twins
  fingerprints are different.

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Twins - minutiae
Image courtesy R. Henderson C. Henderson, 2006
RH Left middle finger
CH Left middle finger
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How to take a fingerprint

• An easy way is to use a pencil
• 1) Rub an area on a piece of paper with a
  pencil. 
• 2) Then rub your finger over the graphite on the
  paper. 
• Next, apply a small piece of sticky tape to the
  finger, lift and place the tape on the sheet of
  paper.
• Make sure you clearly indicate from which finger
  the sample is from.

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An easy way to take a fingerprint
Photograph Paul Ricketts, 2006
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An easy way to take a fingerprint -2
Photograph Paul Ricketts, 2006
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An easy way to take a fingerprint -3
Photograph Paul Ricketts, 2006
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Brushing for a fingerprint at a crime scene
Image courtesy J.Dook, 2006
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Finding Fingerprints

• Some fingerprints are obvious - these are called
  visible prints.

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Visible fingerprints on a door
Photograph Paul Ricketts, 2006
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Finding Fingerprints

• Some fingerprints are NOT obvious - these are
  called latent prints.

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How do you find latent prints?

• Certain chemicals attach to substances that have
  been excreted by the sweat pores.

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Using superglue
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Using iodine
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Using ninhydrin
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References

• Images
• Fingerprints of J. Dook, R. Henderson and C.
  Henderson were taken using a pencil as described
  on Slide 17. The prints were then scanned into
  Adobe Photoshop at a resolution of 1200dpi.
• J. Dook is the hand and foot model.
• Slide 18 image taken of Police Constable Darren
  Fisher by J. Dook at the Joondalup Police
  Academy, November 2005.
• All other photography by Paul Ricketts, DUIT
  Multimedia, the University of Western Australia.
• Graphic design of slides by Trevor Hutchison,
  DUIT Multimedia, the University of Western
  Australia.