Unit 10- Impression Flashcards
Patent impressions
- visible
- 2 dimensional
- bloody shoeprints
latent impressions
hidden
- visualized by chemical or physical development
plastic impressions
- 3 dimensional imprints
- usually in snow or soil
electrostatic dust print lifting device
a tool that electrostatically charges particles within dust or light soil which are than attracted and bonded to a lifted film
adhesive gel lifter
allows lifting of dusty shoe print with a sheet of rubber with adhesive layer on one side
casting with dental stone or plaster
used to collect any plastic or 3 dimensional imprint
difference between class and individual characteristics
class: characteristics that are common among a group of footwear/tire
- ex: size, brand/logo, tread design
individual: unique characteristics observed only on an individual footwear/tire
ex: cuts, scratches, debris, wear pattern
information from shoe impressions
- size
- brand.
- weight
- lifestyle
-gender
impression evidence database (3)
- threadmark (footwork impression database).
- solemate: over 30000 footwear reference database
- threadmate: reference collection containing over 8500 vehicle types
conclusions for impression evidence (3)
- k cannot be eliminated as the source of Q impression
- q impression is identified as originating from K source
- K is eliminated as a possible origin of the Q impression
ridge characteristics (minutiae)
- individual characteristics
- the identity, number, and relative location of characteristics that impart individuality to a fingerprint
- 150 minutiae
- most are partial impressions
3 fundamental principles of fingerprints
- fingerprints are individual characteristics
- a fingerprint remains unchanged during an individual’s lifetime
- fingerprints have ridge patterns that permit them to be systematically classified
points of identification
- number of ridge characteristics that are necessary to identify two fingerprints as the same.
- 8-16
international association for identification (IAI)
NO bases exist for requiring a predetermined minimum number of friction ridge characteristics which must be present in two impressions in order to establish positive identification
fingerprint ridges are found on
-fingerprint and thumbs
-palms
-soles of the feet
3 general patterns
- arch: 5%- does not have a core nor deltas
- loop: 65%- one or more ridges enter from one side, recurve, and exit from the same side
- radial: loop opens toward the thumb
- ulnar: loop opens toward the little finger - whorl: 30%- must have at least 2 deltas
AFIS and characteristics examined
- criminal history and fingerprint database
- general core axis, pattern type, bifurcations, ending ridges
ACE-V
- analysis:
- comparison
- evaluation:
- verification:
two factors in latent printing
- sweat
- contamination
factors affecting fingerprints
- age
-fine ridge structure - stimuli
- occupational and medical condition
- transposal factors
- environmental factors
It is NOT possible to determine the
age, sex, race
patent fingerprints
- visible prints
- left on a smooth surface when blood, in or some other liquid comes into contact with the hands and is transferred to the surface
plastic fingerprints
actual indentions left in some soft materials such as clay, putty, wax, or dust
latent fingerprints
- hidden prints
- caused by transfer of oils and other body secretions into the surface
- can be made visible my different methods
development of latent fingerprints
- fingerprint powders (applied to a non-observant surface
- ninhydrin (reacts with amino acids to form a purple-blue print)
-physical developer ( silver nitrate based solutions) - cyanocrylate fuming ( nonporous surfaces)
- DFO (porous- reacts w/ amino acids)
- iodine fuming (adheres to grease/oils on porous surface)
