Finger Printing Flashcards
fingerprint
an imprint made by the fiction ridge patterns on the last joint of the finger
friction ridge
one of the corrugated ridges characteristic of the skin of the palmar & plantar surfaces of primates
what kind of finger prints are indistinguishable?
human, chimp, and koala prints
what are finger prints composed of?
- ridges
- grooves
ridge colors on print
black
groove colors on print
grey color
four factors that determines the value of associative evidence
- the specificity or degree of identity of the evidence
- the frequency of occurrence
- the persistence of the transferred material
- the likelihood of alternate explanation
why fingerprints can be used as associative evidence
- uniqueness
- persistence
fingerprint uniqueness
- fingerprints are unique to the individual
- no two people have been observed to have the same fingerprint
do identical twins have the same finger print or forensic genotype?
forensic genotype
fingerprint persistence
fingerprints are persistent morphological features that do not significantly change through time
affect of age on friction ridges
- surface ridges flatten making the appearance less sharp when recovered
- numbers of wrinkles increases
exceptions to fingerprint persistence
- considerable skin damage
- genetic disorders resulting in printless fingerprints
how considerable skin damage can effect finger prints
new scars that are persistent can be used to identified suspects
three categories of finger prints
- latent
- patent
- plastic
latent prints
- invisible to the naked eye
- requires a physical or chemical process to enhance or make prints visible
patent prints
visible prints created when residue, contaminating the finger, are transferred to a hard surface
plastic prints
visible, impressed prints that are made in a soft surface resulting in indentations
details of plastic prints
- less common than patent & latent fingerprints
- relatively easy to locate
- negative prints
common surfaces for plastic fingerprints include
- fresh paint
- putty
- wax
- soap
- grease/oil
- dust
negative print
the resulting finger impression has the opposite features as the associated finger
positive print
- the resulting finger impression has the same features as the associated finger
- elevated residue represents an elevated ridge