Name Block Date

ScT 11 Notes: Fingerprints

A) History of Fingerprints: Fingerprints have been used for many purposes for at least 3000 yrs.

o ________________________ (1000 BC): legal documents were signed by fingerprints

o -prehistory: ancient __________ would sign their works with impressed fingerprints

o -The earliest written study (1684) is Dr. Nehemiah’s paper describing the patterns he saw on human hands under a microscope, including the presence of ridges.

o -In 1788, Johann Mayer noted that the .

o - were described in 1823 by Jan Evangelist Purkyn

o -Sir William Herschel in 1856, began the collection of fingerprints and noted they were ___

o -Alphonse Bertillon created a way to identify criminals that was used in 1883 to identify a repeat offender.

o -In 1888, Sir Francis Galton and Sir Edmund Richard Henry, developed the fingerprint _________________________ that is still in use in the United States.

o -1910: the 1st person in the US was convicted based on fingerprint evidence

o -In the 1920’s Federal _____________ began to use them to ____________________________

o -1934: famous gangster ___________________________ paid a doctor $5000 to change his face and “remove” his fingerprints by treating his fingertips with acid. The skin grew back and the scars had the same fingerprint pattern

B) What are Fingerprints? -there are _________________ (valleys) and _______________________ (hills) on . The friction ridges are used to help you .

-every person has a ___________________ pattern of friction ridges that _______________________ throughout their lifetime. These patterns can be used to identify someone.- on these surfaces leave behind an impression (a print) on those objects with which we come in contact. These prints are called ______________-no two individuals make the same fingerprint,

• This is due to the way they are formed: they randomly grow while in the womb• Some qualities are inherited (whorl or loop)• Friction and pressure affect their final outcome

C) Matching & Classifying PrintsThere are 3 main types of patterns to fingerprints.Type Description Pictures How

Commonlines that rise in the centre to create a wave-like pattern. There are “plain arches” and more pointy, “tented arches.”

lines that double back on themselves (do a 180° turn).

lines that look like little whirlpools. They can be spiralled, or look like bull’s eyes. They can look like loops with whorls at the end, or like 2 colliding loops that meet to produce an S-shape

-characteristics for distinguishing fingerprints:1) ________________________________

• Can be used to determine if a print is a loop, whorl or arch• Look like river deltas ( regions )• _

2) __________________ (the center of a whorl or loop) 3) A ridge count: count

Fingerprints are usually matched by a computer program called AFIS ( ) that was introduced in the 1960’s. This computer program can compare about 50,000 prints per second to see if 2 fingerprints match. Before this time, fingerprints were matched by classification and visual inspection (a LOT OF WORK!)

D) Exposing and Collecting Prints1) There are 3 main types of fingerprints made at crime scenes

a) print: really prints- made by fingers coated with dirt, blood, ink, paint, grease, etc.

b) print: print -made by fingers pushed into soft substances like mud, soap, wax, cold butter,

chalk, etc.c) print : prints that can be seen only with special lighting or with processing. Easiest to find on smooth,

hard, shiny surfaces-Made up of

– _________________, picked up from areas that contain hair– _________________________, also from areas that contain hair– Salt, from _____________________________ – ____________________________, from sweat

2) Exposing latent prints (necessary so that they can be seen!)

a) _____________________ : 1) carefully brush a fine powder over the latent print that sticks to the moisture

and oils-usually use a colour that has high contrast to the surface and is usually made of

____________ (black) or aluminum (grey)-some powders ____________ under special laser lighting making them easier to see2) after powdering, the print is ________________________________ 3) print is then by a strip of pressed to the powdered print4) The tape and powder are onto a white card.

b) Chemicals: some chemicals react with latent fingerprints to make them more visible

a) ___________________________ mixed with sodium hydroxide (oven cleaner) and heated will release fumes that stick to fingerprints and ______________________, making them much sturdier and making them more 3-D. Investigators have portable wands that make these fumes that they can use more quickly than fingerprint powders.b) ___________ fumes: _____________ but the brown iodine stain ____________ quickly

c) ___________________: sprayed on and __________________ reacts with print to make it purple. Stain is _______________________.

3) Enhancing prints- can be enhanced by computer programs to

make detail of the ridge pattern more clear.