Fingerprinting Flashcards
What percentage of crime scenes will you find fingerprints?
67%
of prints found at crime scenes what percentage are identified?
37%
how much time does it take to determine if someone is in the AFIS system?
30 min
Is NIJ american or canadian
American
what is NIJ
national institute of justice
what are the 6 classes of fingerprints?
whorl,
right loop,
arch,
tented arch,
left loop,
and double loop
how many primary glands contribute to production of sweat?
3
what are the glands that contribute to production of sweat?
eccrine
apocrine
sabaceous
what compounds are in eccrine glands? how big?
urea, and lactate, small
what compounds are in apocrine glands? how big?
proteins and sugars, very large
what compounds are in sebaceous glands? how big
fatty acids and triglycerides, relatively small
what are proteins made of?
amino acids
what are sugars made of
carbohydrates
where do the chemicals go from the glands?
from pores to friction ridges
a latent print is a ____ of ____ or ____ of the secretions from the three types of glands
mixture of some or all
T/F: amount of secretions from glands are the same across all people.
false some people will only deposit some secretions
what are the classes of surfaces?
porous and nonporous
what does the surface dictate?
the chemistry/reagents used to develop evidence
what are nonporous surfaces (general)
do not absorb and repel moisture often appearing polished
what are examples of nonporous surfaces?
glass, plastic, metal, ceramic, laminant
what are prints on nonporous surfaces more suceptible to?
damage
what kind of developer(s) are used for non porous surfaces?
cyanoacrylate (CA)
how is cyanoacrylate developed on fingerprints?
fuming in a fumehood/enclosed chamber which will come into contact with the fingerprint and a white polymer grows
T/F: butyl-cyanoacrylate can be used to develop prints on non-porous surfaces.
false, ONLY ethyl-cyanoacrylate
what is the common name of cyanoacrylate?
superglue
what are the issues with cyanoacrylate?
- if substrate is white or transparent a secondary technique will be required
- needs chamber and harsh chemicals
- not for onsite applications
- destructive
fingerprints on porous surfaces do what?
absorb into the substrate
what are specific examples of porous surfaces?
paper, cardboard, wood
what can be used to develop prints on porous surfaces?
ninhydrin, flourescent powders
T/F: Ninhydrin reacts with carbohydrates.
false, proteins
why is ninhydrin a good developer for porous surfaces?
because amino acids are stationary when absorbed and do not migrate
which gland will secrete what ninhydrin develops?
apocrine
what is an example of flourescent powders?
1,2-indanedione
T/F: ninhydrin is used as a safer, cheaper alternative to develop fingerprints
false, that is 1,2-indanedione
why does 1,2-indanedione beat everything else?
because it does not matter the background you put it on
what does increased sensitivity mean for LFP development?
you need a dye to help develop
what does signal-to noise ratio mean?
signal is the actual fingerprint, should be very very bright compared to the background (noise)
what does a bandey score of 0 mean?
abscence of any detail, no development
what does a bandey score of 1 mean?
level 1 ridge deteils present, no continuous ridges; they kinda stop abruptly
what does a bandey score of 2 mean?
level 2 ridge details are present; 1/3 of the mark comprised of continuous ridges, remainder is no development or spotty
what does a bandey score of 3 mean?
level 3 ridge details present;
2/3 of the mark comprised of continuous ridges, remainder is spotty/no development
who is the canadian fingerprint expert?
David Ashbaugh
what does a bandey score of 4 mean?
“whole shabang” all continuous ridges.
