Fingerprints
History of Fingerprinting People have always wanted a full proof way to identify someone. The first system was created by Alphonse Bertillon (1883) Used a detailed description plus full length and profile photographs. Also used precise body measurements This included height, reach, width of head & length of left foot.
History of Fingerprinting Police used Bertillon's method for 20 years Early use of fingerprints Chinese used fingerprints to sign legal documents 3000 years ago It was only used in a few places, so no system for identification was created. Around 1880 William Herschel started using handprints for I.D. on contracts in India.
History of Fingerprinting Henry Fauld was a doctor in Japan who wrote an article on how fingerprints could be use for identification. He thought that ridge patterns in the skin could be used to identify criminals. Wanted to pay for a fingerprint bureau at Scotland Yard. He was turned down.
History of fingerprinting 1892 Francis Galton published the textbook fingerprints It suggested methods for recording them Found three types of fingerprint patterns Loops, whorls and arches Showed that no two people had the same fingerprints. Also showed they did not change with time.
History of Fingerprinting Two classification systems for fingerprinting were created. 1) Dr. Juan Vucetich argentine police officer - His system is still used in most Spanish speaking countries 2) Sir Edmund Richard Henry - His system is used in most English speaking countries.
Adoption of Fingerprinting Bertillon s body measurement system had problems. The measurements were not always accurate 1903 convict Will West is sent to Fort Leavenworth Prison. There was already a Will West in the prison. The two men looked identical and had identical measurements.
Adoption of Fingerprinting You could only tell them apart by fingerprints The first official use of fingerprinting was in New York city in 1901. Was used to certify civil service applicants Police, firemen, postmen, etc. 1924 FBI and Leavenworth prison records put together to make a fingerprint database
Adoption of Fingerprinting FBI has the largest collection of fingerprints in the world. By WWI (1912), all of Europe was using fingerprinting for identification.
Fundamental Principles of Fingerprints There are three basic principles 1) No two fingerprints have yet been found to possess identical ridge characteristics. About 64 billion different possibilities for a fingerprint. Odd extremely small two people would have identical prints. In 110 years, no two have been identical
Fundamental Principles of Fingerprints It is based on ridge characteristics = ridge endings, bifurcations, enclosures and other ridge details which must match in two fingerprints to establish a common origin. Not only do the parts of he ridges have to match, they must be in the exact same location on the finger. In court, a point by point comparison is made, using charts, numbers and descriptions.
Fundamental Principles of Fingerprints
Fundamental Principles of Fingerprints Full prints are easy to identify Up to 150 individual ridge characteristics Most crime scene prints are partial prints or smudges. Experts disagree as to how many ridge characteristics are needed to identify someone. Ranges from 8-16
Fundamental Principles of Fingerprints Fingerprint identification is entirely dependent on the experience and knowledge of experts.
Fundamental Principles of Fingerprints 2) A fingerprint remains unchanged during an individual s lifetime. Fingers and thumbs, palms and soles of feet have friction ridges for better grip. The shape of these skin ridges are what we see when we look at fingerprints.
Skin Fundamental Principles of Fingerprints Made of several layers of cells 1) Epidermis outermost layer 2) Dermis inner layer 3) Dermal papillae layer between dermis and epidermis - This layer makes the fingerprints. - This layer develops in the fetus and never changes
Fundamental Principles of Fingerprints
Fundamental Principles of Fingerprints Each skin ridge has a single row of sweat gland pores. This sweat and oil is what is left behind as a fingerprint. Latent fingerprint = an invisible fingerprint made by deposits of oil and/or sweat.
Fundamental Principles Criminals try to change their fingerprints If you go down far enough, it will leave a scar in the dermal papillae This gives us another way to identify the person John Dillinger was a famous mob boss. He dipped his fingers in acid to get rid of his fingerprints. When he died, he was identified by his fingerprints.
Fundamental Principles 3) Fingerprints have general ridge patterns that permit them to be systematically classified. There are three general patterns of fingerprints Loops, whorls and arches 60 65% of people have loops 30 35% of people have whorls About 5% of people have arches
Fundamental Principles Loops have ridge lines that enter from one side of the pattern and curve around to exit from the same side of the pattern.
Fundamental Principles If the loop opens toward the little finger, it is called an ulnar loop. If it opens toward the thumb, it is a radial loop. A type line is ridges that peal away from the loop. A delta is when the type line and loop form a tent shape. The core is the center of the loop.
Fundamental Principles Whorl ridge patterns that are generally rounded or circular and have two deltas.
Fundamental Principles Four types of Whorls 1) Plain whorls have at least one ridge that makes a complete circle. If you draw a line between the two deltas and they touch a ridge. 2) Central pocket whorl has at least one ridge that makes a complete circle. If the line between the deltas does not touch a ridge line.
Fundamental Principles 3) Double Loop two loops in a fingerprint 4) Accidental a combination of forms except for the plain arch.
Fundamental Principles Arches don t have type lines, deltas or cores Least common type of fingerprint 1) Plain arch starts on one side of the finger, makes an arch, goes out the other side. 2) Tented arch same as a plain arch, but comes to a point at the top.
Fundamental Principles
AFIS AFIS = Automated Fingerprint Identification System The Henry system was not easy to use or to store information. Until computers, it was the best we had. 1970 AFIS created computerized identification of fingerprints. 1999 IAFIS Integrated AFIS - This links all 50 states AFIS databases with the FBI s. - Nearly 50 million fingerprints in the system
How AFIS works AFIS We scan and digitally encode fingerprints It puts markers on loops, whorls, arches, ridge endings and bifurcations. Bifurcation = branching of one ridge into two ridges It shows exactly where on the finger each marker is. Can check 500,000 ten finger prints in less than a second.
AFIS
AFIS It has a scrolling system and will kick out a list of prints that most closely match the sample An expert in fingerprints will make the final decision. In No Suspect cases in San Francisco, it identified 1001 people out of 5514 cases (18% If done manually, it averaged 8% Systems will automatically filter out imperfections. It will enhance the image and create a computer image of the print.
AFIS The computer print and the suspect s print are compared side by side by an expert. We no longer use Ink for fingerprints in most places. We now use LiveScan This digitally scan fingers and palms and puts them into AFIS. It only takes minutes to see if they match any other crimes.
AFIS Problems with AFIS Latent prints may not get a hit because the file print is poor. Have to do manual comparisons if this happens AFIS systems are made by several companies All of them do the same thing, but don t do it in the same way. Have different measuring systems & different features They can send information to the FBI, but maybe not to other states.
Detecting Fingerprints Visible prints are not a problem. Latent (invisible) prints require several different techniques to be seen. On Hard surfaces (glass, tile, painted wood), we use powders or super glue fuming. On Soft surfaces (paper, cloth, cardboard), we use different chemicals.
Ways of Detecting Fingerprints RUVIS = Reflected UltraViolet Imaging Systems Lets us see fingerprints on hard surfaces with powders. Shoots UV light which reflects and shows prints They can lift or photograph the print once it has been found.
Finger Print Dusting
Developing Latent Prints 1) Fingerprint powders Fine powder that sticks to sweat and oils on fingerprints Use a camel hair or fiberglass brush to give a light dusting over fingerprint Usually use grey and black powders Use grey for dark surfaces, mirrors and glass Use black for light surfaces. We have magnetic powders in black and grey Used on finished leather and rough plastics
Developing Fingerprints Fluorescent powders can light up a print so you can photograph it. 2) Iodine Fuming Iodine does Sublimation = turning from a solid to a gas with no liquid stage. Put into chamber with evidence, heat crystals and fume the object. This makes the print visible We photograph the prints.
Developing Fingerprints
Developing Fingerprints 3) Ninhydrin This mixes with perspiration in prints Turn the print bluish purple Used on porous surfaces Sprayed with an aerosol can Takes and hour or two for prints to appear. 4) Physical developer Used when the other do not work Used on wet, porous materials
Developing Fingerprints It destroys all of the proteins, so it has to be used last. 5) Super glue fuming Can be used on porous and non-porous surfaces Put super glue on cotton ball mixed with sodium hydroxide Put in a closed cabinet with the evidence and heat. Fumes stick to prints in 4-6 hours.
Super Glue Fuming Alternate Light Source
Developing Fingerprints Can also be used in closed cars. Now we have a hand held version to use on a site. 6) Alternate Light Source Areas have to have chemicals used on it before this can be used Which chemical used depends on what the material is. Need to be an expert to know which one to use
Developing Fingerprints New chemicals for this are being created - None of the chemicals used to find fingerprints mess with the DNA. - Regardless of which method you use, the results need to be determined by a fingerprint analysis expert.
Preserving Developed Prints
Preserving Developed Prints You need a permanent copy for future use Must take a photograph at the scene before you make any attempt at preserving the print. Photo must include where it is in respect to the other evidence. If it is a small object (can, bottle), you can take the whole thing with you. The print should be covered with cellophane to preserve it.
Preserving Developed Prints On large objects, the print has to be lifted 1) Dust print 2) Use a wide piece of clear tape 3) Use the tape to pull up the dust with the print 4) Place on a background that will show up the print. Most police use a ready made version of this.
Preserving Developed Prints The tape and cardboard at attached together with a piece of celluloid between them Remove the celluloid, peel tape, stick to powder, press back onto the cardboard.
Digital Imaging for Fingerprint Enhancement
Digital Imaging for Fingerprint Enhancement Digital imaging = a process through which a picture is converted into a series of square, electronic dots known as pixels. Put pixels together to make a digital image. Black and white images are called grayscale images. Black is 0 and white is 255. Pixels can be anywhere between 0 and 255
Digital Imaging for Fingerprint Enhancement The intensity of the pixels can be manipulated by a computer. Once the picture is in digital form we can try several different ways to enhance the image. Colored surfaces make it harder to get a sharp image. Have to digitally remove the colored back ground to get a sharp image.
Digital Imaging for Fingerprint Enhancement If the print is colored (iodine, Ninhydrin), You isolate the print color to make it stand out With scaling and resizing tools, we can enlarge a part of the print for a closer look. The compare function lets you put two images side by side. You can zoom into both images to compare points.