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2 FINGERPRINTS Objectives By the end of this chapter you will be able to Students will be able to transfer their understanding of impression analysis so that on their own, they will be able to differentiate between objects having individual and class physical characteristics that can be analyzed in order to be identified and compared. Students will be able to transfer their understanding of dactylography so that on their own, they will be able to cite evidence of how to identify and analyze the three general fingerprint patterns, and assess the minutiae found in fingerprints in order to prove a positive match. Discuss the history of fingerprinting. Describe the characteristics of fingerprints. Identify the basic types of fingerprints. Describe how criminals attempt to alter their fingerprints. Determine the reliability of fingerprints as a means of identification. Explain how fingerprint evidence is collected. Describe the latest identification technologies. Determine if a fingerprint matches a fingerprint on record. Use the process of lifting a latent print. Goals The student will: identify and analyze patterns and minutiae. apply concepts of dactylography in order to prove a positive fingerprint match. recognize or recall specific vocabulary, such as but not limited to: arch, core, delta, digital imaging, fingerprint, fluoresce, iodine fuming, latent fingerprint, live-scan, loop, ninhydrin, minutiae, patent fingerprint, Physical Developer, plastic fingerprint, ridge pattern, sublimation, Super Glue fuming, ten-card, whorl. Vocabulary 1. arch a fingerprint pattern in which the ridge pattern originates from one side of the print and leaves from the other side. 2. core a center of a loop or whorl 3. delta a triangular ridge pattern with ridges that go in different directions above and below a triangle. 4. fingerprint an impression left on any surface that consists of patterns made by the ridges on a finger. 5. latent fingerprint a hidden fingerprint made visible through the use of powders or other techniques. 6. loop a fingerprint pattern in which the ridge pattern flows inward and returns in the direction of the origin. 7. minutiae the combination of details in the shapes and positions of ridges in fingerprints that make each unique; also called ridge characteristics. 8. patent fingerprint a visible fingerprint that happens when fingers with blood, ink, or some other substance on them touch a surface and transfer the pattern of their fingerprint to that surface. 9. plastic fingerprint a three-dimensional fingerprint made in soft material such as clay, soap, or putty. 10. ridge pattern the recognizable pattern of the ridges found in the end joints of fingers that form lines on the surfaces of objects in a fingerprint. They fall into three categories: arches, loops, and whorls. 11. ten card a form used to record and preserve a person s fingerprints. 12. whorl a fingerprint pattern that resembles a bull s-eye.
3 Chapter 15 Finger Prints & Finger Printing 1. Arch 2. Core 3. Delta 4. Fingerprint 5. Latent Fingerprint 6. Loop 7. Minutiae 8. Patent Fingerprint 9. Plastic Fingerprint 10. Ridge Pattern 11. Ten Card 12. Whorl 13. Plastic Print 14. Points of Identification 15. Fingerprint powders 16. Iodine fuming 17. Iodine spray reagent
4 Chapter 15 Finger Prints & Finger Printing 18. Silver nitrate 19. Ninhydrin 20. Alternate Light Source 21. Inherent Fluorescence 22. Integrated Automated Fingerprint Identification System
5 Historical Development For thousands of years, humans have been fascinated by the patterns found on the skin of their fingers. But exactly how long-ago humans realized that these patterns could identify individuals is not at all clear. Several ancient cultures used fingerprints as markings. Archaeologists discovered fingerprints pressed into clay tablet contracts dating back to 1792 1750 B.C. in Babylon. In ancient China, it was common practice to use inked fingerprints on all official documents, such as contracts and loans. The oldest known document showing fingerprints dates from the third century B. C. Chinese historians have found finger and palm prints pressed into clay and wood writing surfaces and surmise that they were used to authenticate official seals and legal documents. In Western culture, the earliest record of the study of the patterns on human hands comes from 1684. Dr. Nehemiah wrote a paper describing the patterns that he saw on human hands under the microscope, including the presence of ridges. Johann Christoph Andreas Mayer followed this work in 1788 by describing that the arrangement of skin ridges is never duplicated in two persons. He was probably the first scientist to recognize this fact. In 1823, Jan Evangelist Purkyn described nine distinct fingerprint patterns, including loops, spirals, circles, and double whorls. Sir William Herschel began the collecting of fingerprints in 1856. He noted the patterns were unique to each person and were not altered by age. In 1879, Alphonse Bertillon, an assistant clerk in the records office at the Police Station in Paris, created a way to identify criminals. The system, sometimes called Bertillonage, was first used in 1883 to identify a repeating offender. In 1902, he was credited with solving the first murder using fingerprints. Building on this success, Sir Francis Galton (1822 1911) verified that fingerprints do not change with age. In 1888, Galton, along with Sir E. R. Henry, developed the classification system for fingerprints that is still in use today in the United States and Europe. Iván (Juan) Vucetich improved fingerprint collection in 1891. He began to note measurements on the identification cards of all arrested persons, as well as adding all 10 fingerprint impressions. He devised his own fingerprint classification system and invented a better way of collecting the impressions. Beginning in 1896, Sir Edmund Richard Henry, with the help of two colleagues, created a system that divided fingerprint records into groups based on whether they have an arch, whorl, or loop pattern. Each fingerprint card in the system was imprinted with all 10 fingerprints of a person and marked with individual characteristics called a ten card
6 Formation of Fingerprints The individual nature of fingerprints has been known for about 2,000 years, but scientists only recently understood how fingerprints form in the womb. The latest information suggests that the patterns are probably formed at the beginning of the 10th week of pregnancy, when the fetus is about three inches long. Similar prints are formed in many other areas of the body, such as the palms of the hands, the soles of the feet, and the lips. The creation of fingerprints happens in the basal layer, a special layer within the epidermis where new skin cells are produced. In a fetus, this layer grows faster than the epidermis on the outside and the dermis on the inside. Because it grows faster, the layer collapses and folds in different directions, creating intricate shapes between the other layers of skin. The pattern cannot be altered or destroyed permanently by skin injuries, because the outer layer protects it. Characteristics of Fingerprints Fingerprint characteristics are named for their general visual appearance and patterns. These are called loops, whorls, and arches. About 65 percent of the total population has loops, 30 percent have whorls, and 5 percent have arches. Arches have ridges that enter from one side of the fingerprint and leave from the other side with a rise in the center. Whorls look like a bull s-eye, with two deltas (triangles). Loops enter from either the right or the left and exit from the same side they enter.
7 Latent Finger Printing Techniques
8 A fingerprint is an impression of the friction ridges of all or any part of the finger. A friction ridge is a raised portion of the epidermis on the palmar (palm) or digits (fingers and toes) or plantar (sole) skin, consisting of one or more connected ridge units of friction ridge skin. These ridges are sometimes known as "dermal ridges" or "dermal Papillae". Fingerprint-based identification is the oldest method which has been successfully used in numerous applications. Everyone is known to have unique, immutable fingerprints. A fingerprint is made of a series of ridges and furrows on the surface of the finger. The uniqueness of a fingerprint can be determined by the pattern of ridges and furrows as well as the minutiae points. Minutiae points are local ridge characteristics that occur at either a ridge bifurcation or a ridge ending. Fingerprint matching techniques can be placed into two categories: minute-based and correlation based. Minutiae-based techniques first find minutiae points and then map their relative placement on the finger. Exemplar prints Fingerprint Types Exemplar prints, or known prints, is the name given to fingerprints deliberately collected from a subject, whether for purposes of enrollment in a system or when under arrest for a suspected criminal offense. During criminal arrests, a set of exemplar prints will normally include one print taken from each finger that has been rolled from one edge of the nail to the other, plain (or slap) impressions of each of the four fingers of each hand, and plain impressions of each thumb. Latent prints Although the word latent means hidden or invisible, in modern usage for forensic science the term latent prints means any chance or accidental impression left by friction ridge skin on a surface, regardless of whether it is visible or invisible at the time of deposition. Electronic, chemical and physical processing techniques permit visualization of invisible latent print residues whether they are from natural sweat on the skin or from a contaminant such as motor oil, blood, ink, paint or some other form of dirt. The different types of fingerprint patterns, such as arch, loop and whorl, will be described below. Latent prints may exhibit only a small portion of the surface of a finger and this may be smudged, distorted, overlapped by other prints from the same or from different individuals, or any or all of these in combination. For this reason, latent prints usually present an inevitable source of error in making comparisons, as they generally contain less clarity, less content, and less undistorted information than a fingerprint taken under controlled conditions, and much, much less detail compared to the actual patterns of ridges and grooves of a finger.
9 Patent prints Patent prints are chance friction ridge impressions which are obvious to the human eye and which have been caused by the transfer of foreign material from a finger onto a surface. Some obvious examples would be impressions from flour and wet clay. Because they are already visible and have no need of enhancement they are generally photographed rather than being lifted in the way that latent prints are. An attempt to preserve the actual print is always made for later presentation in court, and there are many techniques used to do this. Patent prints can be left on a surface by materials such as ink, dirt, or blood. Plastic prints A plastic print is a friction ridge impression left in a material that retains the shape of the ridge detail. Although very few criminals would be careless enough to leave their prints in a lump of wet clay, this would make a perfect plastic print. Commonly encountered examples are melted candle wax, putty removed from the perimeter of window panes and thick grease deposits on car parts. Such prints are already visible and need no enhancement, but investigators must not overlook the potential that invisible latent prints deposited by accomplices may also be on such surfaces. After photographically recording such prints, attempts should be made to develop other non-plastic impressions deposited from sweat or other contaminates. Students will understand that although we sometimes appear the same on the outside, when we take a closer look we are all very different from one another.
10 Unfortunately, prints found at a crime scene are usually partial, broken, smeared, or otherwise inferior to the perfect specimens found on fingerprint cards, so it s often impossible to do a full comparison. Fingerprint examiners use points of comparison, also called points of identification, to compare unknown fingerprints against known specimens. A point of comparison is an individual feature of a particular fingerprint, such as where a ridge ends or bifurcates or the shape and number of ridges present in a whorl. If sufficient points of comparison exist between two fingerprints, it s reasonable to assume that those two prints were produced by the same finger, even if parts of the questioned fingerprint are missing, smeared, or otherwise obscured. Figure IV-0-2 shows a typical questioned partial fingerprint found on a questioned document. Although some ridge detail is present, it s unlikely that this print could be identified against a known print. Patent fingerprints Patent fingerprints are visible to the naked eye under ordinary light. Visible fingerprints are patent fingerprints made by fingers touching a surface after they have been in contact with ink, paint, grease, soot, blood, or some similar substance. Plastic fingerprints are patent fingerprints left on an impressionable material such as wet paint, modeling clay, tar, putty, wax, soap, and similar materials. Patent fingerprints of either type are ordinarily readily visible to crime scene investigators and may sometimes be photographed or lifted directly. In some situations, patent fingerprints may be treated to increase their visibility or contrast against the background surface. Latent fingerprints Latent fingerprints are invisible to the naked eye under ordinary light, but can be made visible by dusting, chemical development, or an alternate light source. In forensics, the term alternate light source (or ALS) is used generically to describe any bright light source that emits light at a single wavelength or a narrow band of wavelengths. An ALS may emit light at any wavelength from far ultraviolet through the visible spectrum and into the far infrared. For example, a standard black light fluorescent tube or UV LED flashlight is considered an ALS, as is a sodium- or mercury-vapor lamp. Beginning in the 1980s, lasers became widely used forensically as ALSs. Being expensive, bulky, and limited to a single wavelength made lasers less than ideal as ALSs, so in the 1990s lasers were gradually supplanted by portable ALSs that could be configured with filters or slits to emit narrow-band light over a wide variety of selectable wavelength ranges. Nowadays, lasers are seldom used in forensics labs or by crime-scene technicians. After any processing needed to reveal or enhance the print, fingerprints of either type are preserved by photographing them or by lifting them, either by carefully applying transparent lift tape to the surface that contains the fingerprint, peeling the tape from the surface, and transferring it to a card, or by electrostatic lifting, which uses an electrostatically charged sheet of clear plastic to attract powder applied to the fingerprints. It s at this point that the forensic scientist s job ends and the fingerprint examiner s job begins. Various methods are used to reveal latent prints. Some methods are non-destructive, which means if they are tried and fail to reveal prints, other methods may be used subsequently. Other methods notably silver nitrate development and physical developer are destructive, either in the sense that using them precludes using alternative methods to raise the prints or that using them may preclude testing the object for other types of forensic evidence, such as blood or DNA. The method or methods used, and the order in which they are applied, also depends upon the nature (porous, semi porous, or nonporous) and condition (e.g., wet, dry, dirty, sticky, etc.) of the surface that contains the prints, as well as the residue that constitutes the prints, such as perspiration, blood, oil, or dust.
11 Visual examination is always the first step in revealing latent fingerprints. Some latent prints are patent under strong, oblique lighting. Moving small objects to different angles under a fixed light source may reveal numerous prints, as may moving the light source itself when examining larger or fixed objects. Any latent prints that are revealed under oblique lighting are photographed before any subsequent treatment is attempted. Some prints revealed by visual examination may be undetectable by any other method. Done properly, visual examination is completely nondestructive. Done improperly, the handling required for visual examination may smudge or destroy prints that are invisible visually but potentially visible using other methods. After visual examination is complete, the usual next step is to examine the specimen by using inherent fluorescence. Various components of the fingerprint residue including perspiration, fats and other organic components, and foreign materials present on the fingertips when the impression was made may fluoresce under laser, ultraviolet, or other alternate light sources. In a darkened room, the questioned surface is illuminated with the alternate light source and viewed through a filter of complementary color. For example, longwave ultraviolet (black light) tubes emit some visible light in the deep violet part of the spectrum. Viewing a surface so illuminated through a deep yellow or orange filter blocks essentially all the reflected incident violet light, making any inherent fluorescence emitted by the fingerprint residues in the yellow through red parts of the spectrum more clearly visible. The inherent fluorescence method is usable on any surface, including surfaces that cannot be treated with powders or chemical methods, and may reveal latent prints that are not revealed by any other method. Like visual examination, examination by inherent fluorescence is nondestructive. After visual examination and inherent fluorescence examination are complete, other methods may be used to reveal additional latent fingerprints. Fingerprint powders, iodine fuming, and silver nitrate are considered the classic methods because they have been used since the 19th century. Despite their age and the availability of newer methods, all three of these methods, with some minor improvements, remain in use today. Fingerprint powders Fingerprint powders are used primarily for dusting nonporous surfaces such as glass and polished metal, most commonly to reveal latent fingerprints on immovable objects at crime scenes. Powders are often used in conjunction with super glue fuming to enable a lift to be made. A very fine powder is applied to the area that contains the latent print. The powder adheres to the residues that make up the fingerprint. Excess powder is removed by gentle brushing or using puffs of air from a syringe. After the excess powder is removed, the fingerprint is revealed and can be photographed or lifted. Fingerprint powders are available in shades from white through black, which allows the fingerprint technician to choose a powder that contrasts with the background surface.
12 Fluorescent Fingerprint powders are useful for raising prints on printed or patterned surfaces, which might otherwise make it difficult to see the pattern of the print itself. Magnetic fingerprint powders are used with magnetic brushes, which allow excess powder to be removed without touching the print. Magnetic powders are often used to raise latent fingerprints on paper surfaces, an exception to the general rule about powders being used only on non-porous surfaces. Iodine fuming Iodine fuming is used to reveal prints on porous and semi porous surfaces such as paper, cardboard, and unfinished wood. The object to be treated is placed in an enclosed chamber that contains a few crystals of iodine. Gently heating the iodine crystals causes them to sublime (go from solid phase to gas phase without passing through the liquid phase). The violet iodine vapor adheres selectively to fingerprint residues, turning them orange. These orange stains are fugitive, so they must be photographed immediately. After a period ranging from a few hours to a few days, the iodine stains disappear, leaving the specimen in its original state. The developed prints can be made semi-permanent by treating them with a starch solution, which turns the orange stains blue-black. These stains persist for weeks to months, depending on storage conditions. Iodine spray reagent (ISR) Iodine spray reagent (ISR) is a liquid analog to iodine fuming. Like iodine fuming, ISR is used to reveal prints on porous and semi porous surfaces such as paper, cardboard, and unfinished wood, but ISR can be used on specimens for which fuming is impractical. ISR is made up as two stock solutions that are combined to make the working solution. Solution A (iodine) is a 0.1% w/v solution of iodine crystals in cyclohexane. Solution B (fixer) is a 12.5% w/v solution of alpha-naphthoflavone in methylene chloride. The working solution is made up by combining A: B in a 100:2 ratio, mixing thoroughly, and filtering the working solution through a facial tissue or filter paper. The working solution is sprayed onto the questioned surface, using the finest mist possible. Latent prints develop immediately and should be photographed as soon as possible. Silver nitrate Silver nitrate is used to reveal prints on paper and similar surfaces. The surface is treated with a dilute solution of silver nitrate by spraying or immersion. The soluble silver nitrate reacts with the sodium chloride (salt) present in sweat to produce insoluble silver chloride. The surface may or may not be rinsed with water after treatment to remove excess silver nitrate. In either case, the treated surface is exposed to sunlight or an ultraviolet light source, which reduces the silver chloride to metallic silver, revealing the prints as gray-black stains. Careful observation is required to make sure the prints are not overdeveloped, particularly if the surface was not rinsed after treatment. In extreme cases of overdevelopment, the entire surface may turn black. Silver nitrate development is destructive, and so is used only after iodine fuming and other development methods. Three variants of silver nitrate solution are used: a 1% w/v aqueous solution, a 3% w/v aqueous solution, and a 3% w/v ethanolic solution. The alcohol solution is used on surfaces such as wax paper, coated cardboard, and polystyrene foam that repel water and so cause the aqueous solutions to bead. Silver nitrate is used last, if it is used at all, because using it precludes subsequently using any other development method. Silver nitrate may succeed where other development methods fail because silver nitrate reacts with the nonvolatile sodium chloride present in fingerprint residues. Very old fingerprints may have lost all their volatile residues, but the sodium chloride residue remains. Silver nitrate has been used successfully to develop latent prints that are years, decades, even centuries old.
13 Ninhydrin Ninhydrin was introduced in 1954 as the first of the modern fingerprint development methods. In 1910, the English organic chemist Siegfried Ruhemann synthesized ninhydrin (triketohydrindene hydrate) and reported that it reacts with amino acids to form a violet dye that was subsequently named Ruhemann s Purple (RP). Forensic Scientists must have been asleep at the switch, because it wasn t until 44 years later that Oden and von Hoffsten reported in the March 6, 1954 issue of Nature that ninhydrin could be used to develop latent fingerprints. Although amino acids are present in only tiny amounts in fingerprint residues, RP is so intensely colored that ninhydrin development produces stark visible images of latent prints. Like iodine fuming and silver nitrate development, ninhydrin development is most useful for prints on porous surfaces. The questioned surface is simply sprayed with or dipped in a dilute solution of ninhydrin. After a period ranging from a few minutes to several hours, the prints self-develop as purple stains. In some cases, allowing development to continue for 24 to 48 hours reveals additional latent prints. Processing can be sped up by heating and humidifying the treated surface with a steam iron. After development with ninhydrin, prints may be sprayed with a 5% w/v solution of zinc chloride in a 25:1 mixture of MTBE (methyl tert-butyl ether) and anhydrous ethanol. This reagent causes a color shift from purple to yellow-orange and makes the developed prints fluoresce under an ALS. Two variants of ninhydrin solution are used, depending on the surface to be treated. The standard formulation is a 0.5% w/v solution of ninhydrin in a 3:4:93 mixture of methanol isopropanol petroleum ether. The alternate formulation is a 0.6% w/v solution of ninhydrin in acetone. DFO DFO, also known by its chemical name of 1,8-diazafluoren-9-one, operates by the same mechanism as ninhydrin, reacting with amino acids in fingerprint residues to form visible stains. DFO stains are much fainter than those produced by ninhydrin, but DFO stains fluoresce directly, without after-treatment. DFO was popularized by UK police forces, and is still more widely used in British Commonwealth countries than elsewhere. DFO is somewhat controversial. Many experts maintain that DFO is more sensitive than ninhydrin and provides superior detail. Other experts have questioned the reliability of DFO, and prefer to use ninhydrin alone. If DFO is used, it must be used before ninhydrin, PD, or silver nitrate is applied. DFO reagent is a 0.05% solution of DFO crystals in a solution made up of methanol:ethyl acetate:acetic acid:petroleum ether in a 20:20:4:164 ratio. Cyanoacrylate Vapor Cyanoacrylate is known by its trade name Super Glue. When heated or mixed with sodium hydroxide, cyanoacrylate releases vapors that bind to amino acids that are present in the print residues of a person, thus forming a white latent print. After a print has been exposed with cyanoacrylate, the fingerprint can be photographed.
14 CASE STUDIES Stephen Cowans (1997) On the afternoon of May 30, 1997, Boston police officer Gregory Gallagher was shot with his own gun in a backyard in Roxbury, Massachusetts. Still carrying the gun, the assailant ran to a nearby residence, where he received a glass of water as he wiped off the gun. Stephen Cowans was eventually identified as the shooter. Investigators found a print on the glass used by the individual. The print was matched to prints of Cowans by two fingerprint examiners with the Boston Police Department. Cowans maintained his innocence. With the compelling fingerprint evidence, Cowans was convicted of the shooting and sentenced to 30 to 45 years in the state prison. In 2004, Cowan s defense team requested DNA testing of the glass and a baseball cap dropped at the scene of the shooting. Neither DNA sample matched Cowan s DNA, although they did match each other. The original verdict was overturned. As Suffolk County reexamined the fingerprints as it prepared to retry Cowans, the assistant district attorney discovered conclusively and unequivocally that the purported match was a mistake. Cowans was released from prison after 6. years. As a result, Boston police and the Suffolk County District Attorney s office established new guidelines for identification and evidence handling. Think Critically To get a conviction, I would rather have one good fingerprint than a pound of hair and fiber evidence. Do you agree or disagree? Support your answer.
15 Identifying Finger Prints li
16 Fingerprint Classification & Patterns
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18 Fingerprint Classification & Patterns The usefulness of fingerprints for suspect identification depends on three principles: 1. A fingerprint is individual and is not shared by any two people. Every person has a unique set of fingerprints. Even though identical twins have the same DNA, they have different fingerprints. 2. A fingerprint remains unchanged throughout life. The fingerprints you re born with are the same ones you fie with. If someone burns or shaves off the pads of his fingers, the prints disappear for a while, but as the skin repairs itself and wounds heal, the fingerprints reappear. Nonetheless, completely obliterating a fingerprint is difficult, and any scars left behind by attempts to do so create new individual characteristic that an examiner can use for making a fingerprint match. 3. Fingerprints exhibit general patterns that provide a basis for classification. General patterns exist within every person s prints and all people share these patterns to varying degrees.
19 Identifying Finger Prints Ridge Characteristics
20 Identifying Finger Prints Ridge Characteristics
21 How Reliable Is Fingerprinting as a Means of Identification? Many experts claim that fingerprint identification is flawless. However, humans input and analyze the information, and humans make mistakes. In 1995, 156 fingerprint examiners were given a test. One in five examiners made at least one false-positive identification. More recently, the Federal Bureau of Investigation (FBI) arrested and jailed Oregon lawyer Brandon Mayfield based on fingerprint evidence that linked him to the Madrid train bombings in 2004, which killed 170 people. Mayfield, who had not traveled out of the United States for 10 years, claimed the fingerprint was not a good match. Mayfield was held in custody for two weeks, until the Spanish authorities told the FBI that the mark was, in fact, that of an Algerian citizen. In light of the fallibility of human nature, and the serious consequences of making a mistake, it is important that fingerprint examiners be held to a high standard of performance. Results need to be checked and double-checked to prevent false convictions and to maintain the integrity of the science. How Are Fingerprints Analyzed? Contrary to what we see on television, fingerprint matching is not carried out by a computer in a matter of seconds. By 1987, the FBI had 23 million criminal fingerprint cards on file, and getting a match with a fingerprint found at a crime scene and one stored on file required manual searching. It could take as long as three months to find a match. In 1999, with the cooperation of the national law enforcement community, the FBI developed the Integrated Automated Fingerprint Identification System (IAFIS or AFIS). The IAFIS provides digital, automated fingerprint searches, latent searches, electronic storage of fingerprint photo files, and electronic exchange of fingerprints and test results. It operates 24 hours a day, 365 days a year. Now agencies submitting fingerprints electronically for matching can expect results for criminal investigations within two hours. Currently, the IAFIS maintains the Criminal Master File, which is the largest database of its kind in the world. It contains the fingerprints and criminal histories for more than 47 million people. State, local, and federal law enforcement agencies submit these data voluntarily. Federal and state fingerprinting agencies do not pool their databases. How Are Latent Fingerprints Collected? Latent fingerprints are not visible, but techniques can bring them out. Dusting surfaces such as drinking glasses, the faucets on bathroom sinks, telephones, and the like with a fine carbon powder can make a fingerprint more visible. Tape is then used to lift and preserve the fingerprint. The tape with the fingerprint is then placed on an evidence card on which the date, time, location, and collector of the print is logged. Proper evidence collection techniques involve photographing the fingerprints before they are lifted. Metal or magnetic powders can also be used. They are less messy than carbon-based powders
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