Unit 2

List the 3 principles of fingerprinting

• A fingerprint is an individuals characteristic

• A fingerprint pattern will never change for an individual’s lifetime

• Fingerprints have general characteristics called ridge patterns

List the 3 purposes or uses for fingerprints in identification

• To identify suspects in criminal investigations

• To verify personal identity

• To identify victims in accidents or disasters

Why would an investigator need to wear gloves when dusting for fingerprints

To avoid leaving their own prints and contaminating the evidence

What are the different matrix substances that can leave fingerprints behind at a crime scene

• Sweat

• Blood

• Dirt

• Oil

• Grease

Which matrix substances need to be processed

• Sweat

• Oil

What is meant by the term exemplar print

Known fingerprint taken directly from a specific person to compare with unknown or crime scene print and confirm identity

Porous surface

• Absorb sweat and oils

• Chemical methods like Ninhydrin or iodine are used to reveal prints

• Example: Paper, wood, and cardboard

Nonporous surface

• Don’t absorb residue

• Powder dusting, tape lifting, dye stains, or super glue fuming are used to reveal prints

• Example: Glass, metal, and plastic

Do identical twins have the same fingerprints

No, even identical twins have different fingerprints

What are the small ridges that are raised portions of the skin called

Dermal ridge or friction ridges

What are the imprison left by the ridges called

Fingerprints

How is the fingerprint imprint left

• Natural secretions of sweat glands

• Dirt

What type of evidence are fingerprints classified as

• Individual evidence

• Class evidence

Where do fingerprints begin to form

Basal layer of the skin

When do fingerprints begin to form

10th week of development

Why does every person have a unique fingerprint

Due to different movement patterns within the womb

What is the purpose of fingerprints

Friction ridges allow for gripping

Can fingerprints be removed

No it cannot

Where do fingerprints occur

Dermis of our skin

Target area of a fingerprint

Cluster of 2-3 minutia

Anchor of a fingerprint

Fixed point or main feature (Like the core or delta) that investigators use to compare and match prints

How are the target area and anchor of a fingerprint used to compare fingerprints

Both help examiners line up and compare prints accurately

List the 3 types of fingerprints

• Patent prints

• Plastic prints

• Latent prints

Patent prints

Left on a smooth surface where blood, paint, grease, or other materials come in contact with people’s hands

Describe the techniques used to collect patent prints

Photograph

Plastic prints

Indentations left in materials such as clay, putty, or wax

Describe the techniques used to collect plastic prints

• Photograph

• Mold castings

Latent prints

• Not visible to the naked eye

• Caused by the transfer of oils to the surface

• Made visible by dusting with powders or lifting tape

Describe the techniques used to collect latent prints

• Dusting

• Tape lift

• Fuming

When dusting for latent prints, what is left behind on the surface by a fingerprint that the dust will adhere to since it can’t be seen by the naked eye

• Sweat

• Oil

List the 2 main components that help define different patterns of a fingerprint

• Core

• Delta

List the 3 specific classes for all fingerprints

• Loop

• Arch

• Whorl

Loop

• Ridges enter and exit from the same direction with a center core

• Most common

• Has one or more ridges that enter and exit on the same side

• 1 delta

Arch

• Ridges that enter from one side and exit from the other side with a rise in the center

• Simplest type of fingerprint

• No delta is present

Whorl

• Ridges will form a bull’s-eye appearance with a core at the center

• Have at least one ridge that makes a complete circuit

• Most diverse type of print

• They also have at least 2 deltas

List the 2 types of loop

• Radial loop

• Ulnar loop

Radial loop

• Open towards the thumb or the radius

• 1 delta

Ulnar loop

• Open towards the pinky finger or the ulna

• 1 delta

Why is it important to know which hand (Right or left) the print came from when determining the loop pattern

• Because radial and ulnar loops depend on the hand’s direction

• Radial loops open toward the thumb side, and ulnar loops open toward the little finger

• Knowing which hand it is tells you which side is which

List the 2 types of arch

• Plain arch

• Tented arch

Plain arch

• Raise in the middle with ridges entering and exiting both sides

• No delta

Tented arch

• Sharp rise the center of the ridges

• 1 delta

List the 4 types of whorl

• Plain whorl

• Central pocket whorl

• Double loop whorl

• Accidental whorl

Plain whorl

• Deltas intersect the ridges

• One or more ridges that make a complete spiral

• 2 deltas

Central pocket whorl

• The deltas do not intersect

• One or more ridges that make a complete spiral

• 2 deltas

Double loop whorl

• Made up of any 2 loops combined into one print

• 2 loop formations

• 2 deltas

• Looks like an “s”

Accidental whorl

• 2 or more deltas and a combination of other 2 patterns

• The other patterns cannot be a plain arch

Delta pattern

• Triangular ridge pattern

• We are ridge patterns diverge or change direction

• Can be seen in all 3 basic ridge patterns of fingerprints

What is meant by the ridge count of a fingerprint

Number of ridges between the core and the center of the delta

How is the ridge count determined

A line is drawn from the center of the loop to the center of the delta and the number of ridges are counted

Minutiae

• Unique ridge characteristics of fingerprints

• Everyone has a unique minutiae

How are minutiae like on each hand

Different on right and left hand

Fingerprint identification

Recognizing minutiae, their number, and location

How many individual ridge characteristics are on a fingerprint

150

What do examiners need to determine

If its a partial print, multiple prints, or a print from right or left hand

Incipient ridge

• It looks lighter and less developed, often forming early or partially during fingerprint growth

• Under developed bridges that may or may not show print, depending on the pressure the owner of the fingerprint had applied

List the 7 different aspects of the print that will be analyzed by specialist

• Creases

• Minutia

• Scars

• Tolerance

• Size and shape

• Anatomical region

• Ridge flow

Ending ridge

Picture

Island ridge

Picture

Fork

Picture

Dot

Picture

Bridge

Picture

Spur

Picture

Eye

Picture

Double bifurcation

Picture

Delta

Picture

Trifucation

Picture

How many minutiae are required to confirm a match on a finger

8

How many minutiae are required to confirm a match on a palm

10

How many minutiae are required to confirm a match on a toeprint/footprint

12

Percentage of people with loops

60%

Percentage of people with whorls

35%

Percentage of people with arches

5%

FBI

Federal bureau of investigation

BCI

Bureau of criminal investigation

CODIS

Combined DNA indexing system

AFIS

• Automated fingerprint identification system

• Speeds up fingerprint matching

How many prints are currently stored AFIS

Over 70 million prints

Anthropometry

Study of human body measurements

Why would a person have their prints in the AFIS system

• If arrested

• Employed by government

• Background check

What is RUVIS

• Uses UV light to find prints without powder

• It uses ultraviolet light to spot prints without any powder or chemicals, letting investigators find and photograph fingerprints quickly without damaging them

Describe the steps of superglue fuming to reveal a latent fingerprint

• Place the object with latent prints in a sealed chamber

• Heat a small amount of superglue so it gives off vapors

• The vapors react with the moisture and oils in the fingerprint

• A white, visible print forms on the surface

• The developed print can then be photographed or dusted for clearer detail