• first systematic attempt - french police expert alphonse bertillion
• bertillion system relied on detailed description of subject, full-length profile photographs & system of precise body measurements (anthropometry)
• 1892 - francis galton publishes 'finger prints'
• british gov adopts bertillion system at his insistence
• next step - creation of classification systems for filing thousands of prints in a logical & searchable sequence
• dr. juan vucetich - classification system used in most spanish-speaking countries
• sir edward howard - classification system used in most english-speaking countries
• 1903 - bertillion system couldnt tell between 2 men (will west & william west); fingerprinting could
• this incident, use by new york city civil service commission 1901, and scotland yard training american cops at the 1904 world fair led to integration in all major us cities
• repro of friction skin ridges in hand bits

basic principles:

• 1.) no two fingers have matched in recorded history
• 2.) remains unchanged throughout life
• 3.) general ridge patterns to classify them
• belongs to one person only
• probability of matching is real small
• no two match blah blah blah
• individuality determined by ridges called minutias
• identity, number, and relative location imparts it

principal 1

• common ridge chars - bifurications, ridge endings, ridge dots, enclosures
• as many as 150 on each finger
• currently no minimum for # of chars present in 2 impressions to establish pos id (around 12-13 base)
• expert must do point-by-point compari (map out) prints to prove id

principal 2

• dont change over time
• epidermis = outer, dermis = inner
• dermal papillae = layer of cells between epi- & dermis. determines chars
• once dermal papillae develops in fetus, patterns don't change (aside from getting bigger lmao)
• each skin ridge has pores to sweat
• oils sweated out finger leaves print
• ones left like that are invisible = latent fingerprints

principle 3

• classified systematically
• 3 classes - loops, arches, whorls (l.a.w.)
• 60-65% of pop have loops, 30-35% have whorls, 5% have arches

loops

• 1< ridges entering from one side, re-curving, and exiting from same side
• opens toward pinkie = ulnar loop
• opens toward thumb = radial loop
• pattern area surrounded by 2 diverging ridges aka type lines
• delta = ridge point where 2 type lines diverge; all loops must have 1 delta
• core = approx center of loop

arches

• least common; 2 groups - plain & tented

Vplain is formed by ridges entering from one side, rising and falling, and exiting on opp side (like a wave)

• tented is similar but instead of rising smoothly at center, there'sa sharp spike, or ridges meet at >90 degree angle
• don't have many chars

whorls

• 4 groups - plain, central pocket loop, double loop, accidental
• all whorls have type lines and at least 2 deltas
• plain whorl & central pocket loop have at least 1 ridge that makes a complete circuit
• if an imaginary line drawn between 2 deltas within these patterns touches any circular ridge, it's a plain whorl
• if no such ridge is touched, it's a central pocket loop
• double loop = 2 loops combined into 1 fingerprint (my right thumb)
• accidental either contains 2+ patterns,or is a pattern not covered by other categories. may consist of a combo loop & plain whorl or loop & tented arch

ace-v

• 4-step process to id & individualize a fingerprint:
• analysis - id points of comp & ext factors
• comparison - comp the questioned print at 3 levels
• evaluation - determine a concl
• verification - examiner's concl is confirmed by a 2nd examiner
• there are 3 levels of comp:
• lvl 1 - general ridge flow & pattern config
• lvl 2 - locate & comp ridge chars/minutiae
• lvl 3 - exam & location of ridge pores, breaks, creases, scars, & other permanent minutiae

primary classification

• using primary classif, all print cards in the world could be divided into 1,024 groups
• fingers paired up, placing one finger in the numerator of a fraction & other in the denominator
• presence or absence of whorl patt is basis for determination of primary class
• if whorl pattern found on any finger in first pair, assigned value of 16; 2nd pair = 8; last pair = 1
• any finger with a loop/arch = 0

after all 10 obtained, totaled up & 1 added to numerator & denominator

• fraction obtained = primary class
• approx 25% of pop falls into 1/1 category (all fingers have loops or arches)
• a fingerprint class system can't determine an individual by itself; gives fingerprint examiner a set to look through