l3 impression evidence Flashcards
purpose of friction skin ridges
provide firmer grip and resist slippage
the value of ridge patterns are of (more,same,less) value of type and position of ridge characteristics in determining uniqueness of a print
less than
t/f its possible to obsure ones fingerprints by scarring
false
t/f ridge characteristics are ridge endings, bifurcations, enclosures and other ridge details, which must match in two fingerprints to establish a common origin
true
two major reasons fingerprints are useful
unique to each individual, do not change over time
ridge
single curved segment
furrow
region between two adjacent ridges
pore
found on a ridge
two ways fingerprints are produced
- deposition of sweat
- finger contaminated with another material
what are visible fingerprints?
fingers touching a surface after being in contact with a coloured material
what are the two types of visible fingerprints? what do they mean?
patent- obvious/evident when finger is contaminated
plastic- finger touches pliable surface
what are latent fingerprints?
finger touches a surface, perspiration/oils leave an impression
t/f latent fingerprints visible to the naked eye
false
how long does each type of fingerprint last? (patent, plastic, latent)
plastic- as long as impressed material is intact
patent- fragile, do not last long
latent- years in proper environment
t/f it is possible to determine the age of a fingerprint
false
most important factor in how well a fingerprint is formed
contact time
fingerprint patterns are seen as what type of evidence?
class
loops and whorl patterns contain..?
cores and deltas
what is a core?
approximate center of fingerprint
what is a delta?
point on ridge where there is triangulation or point of divergence
most complex type of fingerprint pattern
whorls
after pattern is identified, …. are used to individualize a fingerprint
minutiae
t/f there is a standard point for the amount of minutiae needed
false
how many minutiae are usually sufficient?
8-16
the important part is not that you have minutiae, but …
location of minutiae in relation to each other
two factors causing unusual fingerprints
skin diseases, genetic diseases
two illumination techniques for seeing prints
- oblique lighting (angle)
- UV/laser (after dye)
enhancement techniques are used to…
enhance contrast b/w print and surface
powder dusting
brush used to dust powder that sticks to sweat components
chemical enhancement and example
exposes the fingerprint to fumes, ex superglue fuming to crystalize print
what type of characteristics are minutiae considered as?
individual
fingerprints are studied for the… of ridge characteristics/minutiae
(3pts)
kind, number and location
t/f most prints recovered are full, intact prints
false, usually partial prints
what does Automated Fingerprint Identification System allow us to do?
storage and search system, can place two print images side by side
