chemical enhancement

• what can we use for porous

  idandione

  ninhydrin

  physical developer
• what can we use on non porous

  superglue

  polycyano
• porous

  paper

  cardboard
• non porous

  plastic

  metal

  bags
• behaviour of porous

  soaks into surface
• behaviour of non porous

  sits on surface
• what other forensic evidence

  paper - indentations, ink, physical fit

  plastic bags - fibres, physical fit

  plastic bottles/ can - DNA

  sticky tape - fibres, DNA, physical fit
• any question to recovering fingermarks on porous surfaces

  • visual examination
  • fluorescence examination
  • idandione (most effective)
  • ninhydrin
  • physical developer
  • physical developer enhancement
• any question to recovering fingermarks on non porous surfaces

  • visual examination
  • fluorescence examinatin
  • vacuum metal deposition
  • powders
  • superglue fuming
  • superglue fuming enhancement
  • lipid dye
• what is idandioine

  developed from ninhydrin

  reacts with the amine group

  fluoresces orange
• how does idandione work

  photograph

  working solution

  dry

  heat at 100 degrees for 10 mins

  photograph
• what is ninhydrin

  crystalline solid

  reacts with amine group

  immediate visible prints
• positives of amino acid reagents

  simple

  cheap

  fluoresces
• negatives of amino acid reagents

  wont develop on surfaces exposed to water

  not perm
• how does physical developer work

  photograph

  maelic acid to wash ninhydrin and amino acids

  working solution for 10 mins

  rinse with water

  wash

  photograph
• negatives of PD

  laborious and slow
• what is superglue fuming

  causes salt crystals to form
• how does superglue fuming work

  take an aged mark and rehumidify it by adding water causing salt to split into sodium and chloride ions

  add superglue

  add yellow 40 dye to improve contrast
• conditions for superglue fuming

  120 degrees

  80% humidity
• positives of superglue fuming

  easy

  use on a wide range of non porous surfaces

  can recover large articles of surfaces
• negatives

  requires a chamber

  difficult to see marks

  cant use on porous
• how does AB1, AV17, AY7

  sulphosacylic acid

  working solution for 10 minutes

  wash
• positives of the As

  7 fluoresces as its most sensitive

  simple

  cheap
• negatives of the A

  only use for bodily fluids

  flammable working solution

  can damage surfaces
• enhancement strategies

  document the exhibit before enhancement via notes and photographs

  document your enhancement steps

  start with the less destructive techniques such as fluorescence and visual examinations

  consider the condition of exhibit eg dry or wet