Chapter 4 fingerprints Flashcards
another word for fingerprint?
Dactylogram
the study of fingerprints
dactyloscopy
all _________ have fingerprints
primates
what animal has fingerprints that most closely resembles a humans
koalas
when are fingerprints formed?
in the fetal stage
what was the west will case
in 1903, a prisoner named will west was brought to Leavenworth Federal Penitentiary his Bertillon measurements and photogenic appearance appeared to be identical to another prisoner (William west) serving a life sentence in murder. they were not related -> fingerprints
most common type of fingerprint?
loops
a loop must have
one or more ridges entering from one side of the print, fecurring (?) and exiting from the same side
what is a delta?
a place where two lines run side by side and then diverge with a significant recurring line passes in front of the delta (a triangle is formed)
what’s a ulnar loop?
pattern come sin and goes out toward little finger. left hand.
what’s a radical loop?
pattern comes in and out towards thumb. right hand. not very common. usually found on index fingers.
what’s the percentage of people with whorls?
30-35
whorl patterns must have
- type lines
- at least two deltas
what’s a plain whorl?
consists of one or more ridges which tend to make a complete circuit
what a central pocket whorl?
must have 2 deltas
double loop whorls?
consists of two seperate & distinct loop formations. loops have separate and distinct shoulders. has 2 deltas.
what are arches?
compost about 5% of fingerprints. no deltas.
what is a plain arch?
no delta & no core. lines come in one side of the print and exit the other side without much of a change in patterns.
what’s a tented arch?
no delta. line-type quickly rises and falls at a steep angle
one delta
loop
> 1 delta
whorl
no delta
arch
what is ridgeology
the study of the uniqueness of friction ridge structures and their use for personal identification.
what are minutiae points?
points where ridge structure changes?
what are the 3 way process fingerprints are classified?
- by the shape and contours of individual patterns
- by the finger position of the pattern type
- by the relative size
the Henry- FBI classification
can’t individualize and provides the examiner with a number of candidates with indistinguishable sets of prints in the systems file.
what’s only useful for processing a full set of fingerprints?
the Henry- FBI classification
generally criminal courts will accept _ to __ points of similarity
8 to 12
how does super glue fuming / cyanoacrylate work?
-heat is applied to super glue in a sealed enclosure containing the evidence. heating causes the super glue to vaporize. super glue vapors settle on the evidence and react with the latent print. a visible white outline is formed.
what’s the silver nitrate formula?
AgNO3 + Cl - AgCl -> Ag (in UV)
how does silver nitrate work?
silver nitrate dissolved in water or alcohol is sprayed into the object surface reacts with salt in perspiration.
- spraying or dipping the object in silver nitrate
- developing the print with sunlight or a carbon vapor light
how do powders work?
the most common powders are black & silver. lifted with a special tape & photograph Iodine fuming. excellent way to locate latent finger prints.
development process of hard no absorbent surfaces
powder
development process of soft , porous surfaces
chemical visualization
how does iodine fuming work?
iodine is a substance that sublimes to produce vapors of iodine. it reacts with oils present in fingerprints and it’s stained brown.
what is a fingerprint?
an impression of the pattern of the ridges on the last joint of a persons finger
what is primary classification?
determination of the primary classification is based on the presence or absence of the whorl pattern. presence of a whorl pattern is given a numerical value that depends on the finger on which it occurs.
Right hand
pinky - 4 RING - 8 MIDdle - 8 index - 16 thumb - 16
left hand
thumb - 5 index - 2 middle - 2 RING - 1 pinky - 1
what happened 1788
J.C.A Mayer ridges of the fingers in two or more individuals are NECER identical
what happened in 1892?
Francis Galton Practical shared of classification and filing
what happened in 1900?
sir Edward Richard Henry extended Galtons system
what is anthropometrics
an identification system using body measurements developed by Alphonse
anthropometrics had 3 components the
measurements of the body
measurements of the head
measurements of the limb
what features were in the anthropometrics
- photos
- profile (measurements)
- verbal description
problems with anthropometrics
- time consuming
- difficult to master
- impossible to use bertillonage on a person not arrested
