Transcript fingerprints - Liberty Union High School District
Fingerprints & Footprints Chapter 4 Introduction Fingerprints are a unique pattern of ridges and depressions on the tips of the fingers. They can positively identify that a single person made that print. In the over 140 years that fingerprints have been routinely compared worldwide, no two areas of friction skin on any two persons (including identical twins) have been found to contain the same individual characteristics in the same unit relationship. Other visible human characteristics change fingerprints do not. Introduction Fingerprints offer an infallible means of personal identification. The fingerprint was recognized in Ancient China where it was used to forge contracts. Fingerprints as Forensic Science Fingerprints outperform DNA and all other human identification systems to identify more murderers, rapists and other serious offenders (fingerprints solve at least ten times more unknown suspect cases than DNA in most jurisdictions). Where can fingerprints be found? Fingerprints from crime scenes have been identified on Papers Cigarettes Fruit crumpled aluminum cans plastic garbage bags bed sheets Rocks dead bodies (prints on bodies are usually contaminated prints involving body fluids, lipstick or some other substance transferred via the suspect's fingers) How Long Do Fingerprints Last? Fingerprints on paper, cardboard and unfinished wood can last for up to forty years (per actual casework histories) unless exposed to water (and contaminate transfer prints can even then sometimes persist). Fingerprints on non-porous surfaces such as plastic, metal and glass can last for many years if not exposed to water and if left undisturbed. Formation Fingerprint ridges are formed during the third to fourth month of fetal development. These ridges consist of individual characteristics called Ridge endings Bifurcations Dots The unit relationship of individual characteristics does not naturally change throughout life Classifying Fingerprints Sir Frances Galton, Edward Henry, and Juan Vucetich are all three responsible for classifying fingerprints. Why is this so important? Loops Arches Whorls 65% of the population have ridge patterns that form loops. Approximately 30 percent of the population has whorls 5 % have arches arches – follow a smooth wave like pattern Tented arches – contain a sharp point at the center Plain Revealing & Recording Prints Three main categories of fingerprints: Visible – you can see them (paint, ink) 2. Plastic – made in soap wax or putty 3. Latent – The most common type and hidden to the eye. 1. Latent prints are made when natural oils and perspiration present between the fingerprint ridges are transferred to a surface by touch. Revealing & Recording Prints Methods of lifting prints Dusting with powder Different types of powder and different colors Chemical Use of superglue or cyanoacrylate. Easy to use, low cost. Remarkable results Use of ninhydrin spray that forms a purple color when combined with traces of amino acids in human perspiration. Used on paper and cardboard Amido black, a dye sensitive to blood and may be used with contaminated/visible prints The FBI FBI maintains AFIS The FBI's Integrated AFIS (IAFIS) in Clarksburg, WV has more than 49 million individual computerized fingerprint records for known criminals. Fingerprinting the Dead Pathologists finger print the dead during autopsies. Sometimes reconstructive work has to be done in order to retrieve the fingerprints. Other Identifiers Palm prints, feet prints Has anyone as a baby had their feet inked at the hospital?