FINGERPRINTS

A HISTORY OF FINGERPRINTS A classification system for fingerprints was developed in 1891. Francis Galton published his book "Finger Prints" in 1892 which included the following principles. * There are 3 types of  fingerprint patterns * Prints do not change over time * Prints are unique to the individual. Not even identical twins – who have identical genes have the same prints! Alicia Brown MAI Making Links Forensics, September 2006

HOW ARE FINGERPRINTS MADE? Definition of a "print“: When oil from the body mixes with sweat and dirt and you touch something, these adhere to the surface of the object, leaving a print. Fingerprint identification (Dactyloscopy) is the process of comparing questioned and known prints to determine if the impressions are from the same finger (or palm, toe, etc.). Fingerprints are a very useful resource at a crime scene.  Fingerprints are left everywhere at anytime.  Many cases have been solved with the use of fingerprints.  Alicia Brown MAI Making Links Forensics, September 2006

HOW PRINTS ARE USED IN A CRIMINAL INVESTIGATION? Each time the FBI books a suspect in a crime they make inked fingerprints of the person to be kept on file. About 200 million prints are on file. Computer software can run a set of prints through scanning devices and a match can be found in  minutes. There are at least 150 different ridge characteristics on the average fingerprint. If 10-16 specific points of reference for any two fingerprints identically compare, a match is assumed. In a judicial case, 12 points must match in order to prove the identity of a specific person. Alicia Brown MAI Making Links Forensics, September 2006

Alicia Brown MAI Making Links Forensics, September 2006 TYPES OF PRINTS Human fingerprint patterns fall into three main groups: Arches Loops Whorls Despite these broad patterns, each individual has a unique set of fingerprints, which can be used as a means of personal identification. Alicia Brown MAI Making Links Forensics, September 2006

Alicia Brown MAI Making Links Forensics, September 2006 ARCHES Account for 10 percent of fingerprint. They have lines that start at one side of the print and then move toward the centre of the print and leave of the other side of the print. Arches have no type lines or deltas. Plain Arch - simplest of all the fingerprint patterns. Tented Arch - ridges rise in a sharp thrust or spike in the centre of the print. at an angle less than 90 degrees Alicia Brown MAI Making Links Forensics, September 2006

Alicia Brown MAI Making Links Forensics, September 2006 WHORLS Whorls account for 30 percent of fingerprints. Whorl patterns have a lot of circles that do not exit on either side of the print. All whorls have at least 2 deltas. Plain Whorl - A line drawn between the 2 deltas touches one of the spiral ridges. Central Pocket Whorl - An imaginary line drawn between the 2 deltas does not touch the spiral ridge. Alicia Brown MAI Making Links Forensics, September 2006

Alicia Brown MAI Making Links Forensics, September 2006 LOOPS Loops are the most common type, accounting for about 60 percent of all fingerprints. They have lines that start at one side of the print, and then move toward the centre of the print and leave on the same side of the print they started on. Left Loop - loop opens toward the little finger (ulna) Right Loop - loop opens toward the thumb (radius) Double Loop - any 2 loops combined into one print Mixed figure - contains 2 or more patterns (not including a plain arch) or the pattern is not covered by other categories. Alicia Brown MAI Making Links Forensics, September 2006

FINER DETAILS – WAYS TO DISTINGUISH PRINTS TYPE LINES are the line before the pattern changes. The two diverging ridges usually coming into and splitting around an obstruction, such as a loop. A DELTA is the ridge point nearest the type line divergence. It usually forms a triangle. The CORE is the approximate centre of the pattern. Examples of these characteristics are shown : Alicia Brown MAI Making Links Forensics, September 2006

Types of fingerprints left at crime scenes Visible prints - can be seen with the naked eye Latent prints - are invisible Plastic prints - leave an impression on objects such as soap or wax Alicia Brown MAI Making Links Forensics, September 2006

Methods used to obtain fingerprints There are many methods of obtaining latent prints: Dusting Carbon powder for white/light coloured surfaces * Lanconide powder for black * Aluminum powder for hard or dark coloured surfaces or mirrors and metal surface Fuming * use of super glue (Cyanoacrylate) * iodine * ninhydrin * silver nitrate * Gentian violet Laser technology Alicia Brown MAI Making Links Forensics, September 2006

Alicia Brown MAI Making Links Forensics, September 2006 Now it’s YOUR TURN! Let’s have a go at taking our own fingerprints and then trying to classify them. Use your hand-out to assist. Later, we will use this knowledge to lift a print from the crime scene, classify it and then match it to one of the suspects Alicia Brown MAI Making Links Forensics, September 2006