Unit 4 Fingerprint Identification

Students will explore fingerprint identification

Vocabulary

Dactylscopy Ridge characteristic Minutiae Loop print Whorl print Arch print IAFIS Ridge count Bifurcation Double bifurcation Lake/enclosure Spur Short ridge Island/eye

Dot Bridge/crossover Ridge ending Latent print Visible print Plastic print

Fingerprints:

Dactylscopy is the study of fingerprints. This study began in the 1800’s.

Obj. 1 FUNDAMENTAL PRINCIPLES OF FINGERPRINTING

First Principle: A fingerprint is an individual characteristic, no two fingers have identical ridge characteristics It is not the shape of a print that is

individual, but the number, location and shape of specific ridge characteristics

Specific ridge characteristics are called minutiae

Obj. 1 FUNDAMENTAL PRINCIPLES OF FINGERPRINTING

Second Principle: A fingerprint will remain unchanged during an individual’s lifetime A fingerprint can be obscured by deep

tissue damage such as scars or burns Scars may be useful as points of

identification

Obj. 1 FUNDAMENTAL PRINCIPLES OF FINGERPRINTING

Third Principle: Fingerprints have general ridge patterns which permit them to be systemically classified. Classifying the general pattern of

fingerprints allows them to be stored in a filing system, which then can be retrieved for comparison.

Modern technology allows this process to be transformed to a computer system- IAFIS

Obj. 1 Degrees of Classification

There are three levels or degrees of classification, with each degree being more specific

The first degree of classification is based on the overall pattern of each print, loops, whorls and arches.

any whorl patterns. It is called the 10 print classification system.

Second degree is the identification of minutiae

Third degree is the identification of pores

Obj. 1: 1st degree of Classification

Prints have overall patterns. They are called either loops, whorls or arches.

These overall patterns are not unique. They are class evidence, not individual evidence.

If all fingers have been printed, then the 10-print classification can be determined.

Obj. 1: 10 Print Classification: 1st degree

Developed by Edward Henry and modified by the FBI.

Breaks up all possible sets of fingerprints to be divided into a possible 1,024 groups.

Based on a whorl pattern – must have ALL fingers printed to determine

Obj. 1: 10 Print Classification: 1st degree

Formula:Top: Rt index(16)+ rt ring(8)+ Left thumb(4)+ Left middle(2) + left little(1) + 1 = Bottom: rt thumb (16)+ rt middle (8)+ rt little(4) + left index(2)+ left ring(1) + 1 =

(See next slide) Therefore, if a whorl pattern is

present on any of the fingers, it is assigned a numerical value.

Obj. 1: 10 print formula: 1st degree

Obj. 2: Identifying Fingerprints

The result is written as a fraction The complete code exactly describes the

print in a way people and machines can understand and file

This presents examiners with a manageable list of possible matches for the fingerprint.

Computer matching of fingerprints is used to make the first big cut of matches, after this manual comparison may still be needed.

Obj. 2: Classification of Fingerprints and Ridge Patterns

Fingerprints can be classified into three basic patterns, loops, whorls and arches

Obj. 2: LOOPS

Most common pattern, with 65% of all fingerprints having loops

Fingerprint pattern with one or more ridges entering from one side, curving, then going out from the same side entered

Obj. 2: LOOPS

Loops have two focal points, delta and core▪ Delta- triangular area found in all loop and

whorl patterns▪ Core- area found near the center of all loop

and whorl patterns

Obj. 2: LOOPS

There are two subgroups to the loop, the radial loop and the ulnar loop▪ Radial loop- ridges flow in the direction of the

thumb ( radius)▪ Ulnar loop- ridges flow in the direction of the ▪ little finger (ulna)

European ancestry tend to have more loop patterns on their fingerprints

Obj. 2 WHORLS

Second most common pattern, occurring in 30-35% of all fingerprints

Fingerprint pattern with at least two deltas and a core. Whorls take the form of a spiral, shell, circle, target or eye.

Obj. 2 WHORLS

There are four types of whorls Plain Double whorl- Central Pocket- Accidental

Asian and Oriental ancestry tend to have more whorls patterns on their fingerprints.

Obj. 2 ARCHES

Arches are the least common and the simplest of fingerprint patterns, occurring in 5% of fingerprints

Fingerprint pattern that has no delta or core. All ridges enter one side and exit the other.

Obj. 2 ARCHES

Arches are subdivided into two distinct groups, plain and tented Plain-Ridges tend to rise in the center of

the pattern, forming a wave-like pattern Tented – contain a sharp spike in the

ridges, or the ridges meet at an angle less than 90 degrees.

African American ancestry tend to have more arch patterns on their fingerprints.

Obj. 2 Arches

Obj. 2 Ridge Count

One way to start to individualize prints is to do a ridge count. A straight line is drawn from the central focus to the center of the delta. The number of ridges this line crosses is counted and that number = the ridge count

This works best with loops and whorls where deltas are clearly present.

Obj. 2 Individualization- Ridge Classifications

To individualize fingerprints you must use the fine structure of ridge characteristics, or minutiae.

There are several classes of minutiae to help individualize fingerprints.

For each type, refer to your balloon print and find one example of each type Bifurcation- occurs when a ridge splits or

forks into two separate ridges

Obj. 2 Individualization- Ridge Classifications

Double bifurcation-occurs when a ridge splits or forks into two separate ridges, and then splits again into two separate ridges

Ridge End - abrupt termination of any ridge.

Lake or enclosure -occurs when a single ridge line bifurcates, then quickly reconnects and continues as a single ridge

Obj. 2 Individualization- Ridge Classifications

Island or eye - short ridges that simply start and stop and don’t connect to any other ridge

Dot - a very short island, of basically equal length and width

Bridge -short ridge that runs between two other parallel ridges, sometimes called a “railway tie”

Obj. 2 Individualization- Ridge Classifications

Spur- a special bifurcation where one resulting ridge is considerably shorter, ending near the original split/fork

See the pores? This is the 3rd degree of fingerprint idenification.

Obj. 2 Identifying Fingerprints

There are no legal requirements in the United States on the number of minutiae and their relative location (points) that must match before deciding that a fingerprint belongs to a certain individual.

There are 150-200 minutiae in a properly rolled print.

Criminal courts will generally accept 8-12 points of similarity as sufficient proof. An newer acceptance level of 10 is typical.

Tru TV fingerprint game http://www.trutv.com/shows/forensic_

files/games/fingerprint/index.html

Obj. 2 IAFIS

The Integrated Automated Fingerprint Identification System (IAFIS) is a system maintained by the FBI.

IAFIS provides automated fingerprint search capabilities, latent searching capability, electronic image storage, and electronic exchange of fingerprints and responses.

Obj. 2 IAFIS

IAFIS maintains the largest biometric database in the world, containing the fingerprints and potential corresponding criminal history information for more than 47 million subjects.

Obj. 2 How IAFIS works

This approach has revolutionized criminal investigative used of fingerprints. A computer can make thousands of comparisons in a second, thus increasing the chances of finding a match in a far shorter time than was previously possible.

Shortly after being brought on-line for the first time in 1985 the Los Angeles Police Department's IAFIS helped bring to justice the multiple killer known as the Nightstalker.

Obj. 2 How IAFIS works

The device used for scanning live fingerprints into AFIS is called Live Scan. The process of obtaining the prints by way of Live Scan employs rolling prints or placing flat impressions onto a glass plate above a camera unit.

The process of obtaining prints by placing a ten print card (prints taken using ink) onto a flatbed or high-speed scanner is called CardScan.

Obj. 2 How IAFIS works for a crime scene

A photograph of the print from the crime scene is scanned into a computer.

The image of the fingerprint is compared with the computerized database of prints and a list of possible "hits" is produced.

It is then up to the fingerprint expert to make the final decision as to whether there is match or not.

Obj. 3 COMPARE AND CONTRAST LATENT, PLASTIC AND VISIBLE FINGERPRINTS

Plastic prints are impressions of a fingerprint left in a soft substance such as, wax, soap, putty, gum, stamps, candy bar, or fresh paint. They are also known as indented or molded prints and are not commonly found at a crime scene.

•Plastic prints are impressions of a fingerprint left in a soft substance such as, wax, soap, putty, gum, stamps, candy bar, or fresh paint. They are also known as indented or molded prints and are not commonly found at a crime scene.

Obj. 3 COMPARE AND CONTRAST LATENT, PLASTIC AND VISIBLE FINGERPRINTS

Visible prints are fingerprints that have touched colored materials such as; blood, paint, ink, grease, chalk, mud or dust. Visible prints are not common at a crime scene.

Obj. 3 COMPARE AND CONTRAST LATENT, PLASTIC AND VISIBLE

FINGERPRINTS

Latent prints are fingerprints formed by oil and sweat secretions deposited by a person’s finger when they touch a surface or object. Latent prints are invisible and must be developed by chemical or physical means.

Obj. 3 Developing Prints: Latent Prints

To make latent fingerprints visible they must be developed or treated to make them visible. Once there is a visible print to work with, the next step is to recover it and document its location at the scene.

There are several physical and chemical methods of visualizing latent fingerprints. dusting, staining and chemical fuming are common methods.

Obj. 3 Developing Prints: Dusting

Dusting is the most widely used method of detecting latent finger prints. It is suitable for hard and/or non-porous surfaces. Uses a fine powder that adheres to the traces of oil and sweat. There are several types of powders used to

develop prints examples are: The “developed” print can then be “lifted”

by means of clear sticky tape and collected for analysis.

Developing Prints: Staining

Iodine reacts with the fatty oils from the finger to form a visible but short-lasting print.

Iodine works best for prints on porous paper.

The print will fade over time, but as iodine does not chemically alter the print in any way, it can be re-applied if needed

Developing Prints: Staining

Ninhydrin reacts with the amino acids. commonly used with paper and porous surfaces can be used after iodine fuming Stains a print over a 24 hour period. Can be sped

up with humidity and heat

Obj. 3 Developing Prints: Fuming

Superglue fuming: when superglue is heated it creates fumes which bind to fingerprint oil residues. This makes a white permanent impression that

then can be treated with powders or fluorescent dyes to create a sharper contrast and allows for easier lifting or photography.

Used for developing prints on non-porous surfaces such as metals, glass, plastic articles, adhesive tape and firearms.

Obj. 3 Developing Prints: Lab Work

Silver Nitrate reacts with the sodium chloride (salt) from perspiration.

For very old prints, the sodium chloride may be the only thing left so silver nitrate is the only option.

Silver nitrate is used on porous surfaces, like paper or wood.