Fingerprints and Human Identification

21-09-2010
Forensic dentistry

 

 

1.1 Introduction
Fingerprints have been the gold standard for personal identification within the forensic community for more than one hundred years. The science of fingerprint identification has evolved over time from the early use of finger prints to mark business transactions in ancient Babylonia to their use today as core technology in biometric security devices and as scientific vidence in courts of law throughout the world. Fingerprints, along with forensic dental and DNA analysis, are also paramount in the identification of unknown deceased individuals and human remains. To this end, recent increases in homicides, mass disaster incidents, and combat casualties from wars in Iraq and Afghanistan highlight the vital role that forensic science plays in human/victim identification. While this responsibility is an emerging challenge for many forensic disciplines, fingerprint analysis has been the foundation of forensic identification efforts for decades. This chapter discusses the basics of fingerprint identification and how forensic examiners recover friction ridge impressions from remains in order to identify the dead.

 

1.2 Historical Overview of Fingerprints
We read of the dead body of Jezebel being devoured by the dogs of Jezreel, so that no man might say, "This is Jezebel," and that the dogs left only her skull, the palms of her hands, and the soles of her feet; but the palms of the hands and the soles of the feet are the very remains by which a corpse might be most surely identified, if impressions of them, made during life, were available.

The patterned ridges present on the bulbs of the fingers have been a source of intrigue for humankind since prehistoric times. The appearance of fingerprints on clay pots and documents throughout early civilization indicates the possible recognition of the individuality and value of fingerprints as a means of personal identification. While this observation is debated by historians, there is no debate that the many instances of fingerprints found in the archaeological record set the stage for the scientific development of modern fingerprint identification in the nineteenth century.
The first practical application of fingerprints as a form of personal identification is credited to Sir William Herschel, a British officer based in India, who used fingerprints and handprints as signatures on native contracts to prevent fraud.

Over time, Herschel recognized the value of fingerprint identification and, in a letter written to his superiors in 1877, advocated the implementation of fingerprinting for a variety of civil and criminal endeavors.
At about the same time, Dr. Henry Faulds, a Scottish physician working in Japan, published a letter in the journal Nature (1880) discussing his scientific observations on the identification potential of fingerprints. The pioneering research conducted by Faulds was broad in scope, forecasting the forensic use of fingerprints to catch criminals and describing the contemporary method of recording fingerprints using black printer's ink. His theory regarding the evidentiary value of fingerprints was confirmed when he solved a minor crime involving the pilfering of purified alcohol from his hospital laboratory.
Faulds was able to compare greasy fingerprints found on a piece of glassware with inked impressions he had collected from his staff, identifying one of his medical students as the offender and making what is considered to be the first fingerprint identification in history.

The work of Herschel and Faulds was further expanded upon by Sir Francis Galton in his landmark book Finger Prints, published in 1892. The studies performed by Galton detailed the individuality and persistency of friction ridge skin, providing empirical support to the underlying scientific principles of fingerprint identification. His book also introduced a classification or cataloging system for recorded fingerprint impressions, a necessity for the general acceptance of fingerprints as a means of personal identification.
Although the classification system devised by Galton was limited, it became the basis for a number of more functional and contemporary fingerprint classification methods.
One of the most widely accepted and practicable systems of fingerprint classification involved the labors of an Englishman named Sir Edward Henry. By corresponding with Galton, Henry came to recognize the limitations associated with fingerprint classification and determined that, in order for fingerprints to be used as a systematic means of personal identification, a simplified method was required to allow law enforcement the ability to easily file and retrieve numerous fingerprint records. The creation of such a system was accomplished by Henry and two of his subordinates (Haque and Bose) working in India in 1897. Soon afterward, the resulting Henry classification system was adopted by the Indian government, establishing fingerprints as the official means of criminal identification in India.

Four years later, in 1901, India's fingerprinting success led England and Wales to implement fingerprints as a means of criminal identification and establish a Fingerprint Bureau at New Scotland Yard.

The first official use of fingerprints in the United States began when the New York Civil Service Commission in 1902 and the New York State Penitentiary System in 1903 adopted the use of fingerprints for civil and criminal identification purposes, respectively.

The systematic utilization of fingerprints for personal identification soon became standard operating procedure and spread throughout the United States, as well as the civilized world, culminating in the establishment of a national repository for fingerprints with the newly created Identification Division of the Federal Bureau of Investigation (FBI) in 1924. The repository, which was originally based on a modified version of the Henry classification system, is now an ever-increasing computerized database currently containing over 55 million criminal and 4 million civil fingerprint records.
The identification of human remains through fingerprints is not well defined historically. While Herschel, Faulds, and Galton all suggested the use of fingerprints to identify the dead in the late 1800s, the actual application of fingerprints for this purpose began only after the systematic adoption of fingerprints for personal identification in the early 1900s. One of the first cases involving the use of fingerprints to identify decedents occurred in Birmingham, England, with the identification of a suicide victim in 1906.

Another documented example of the early use of fingerprints for human identification is discussed by Henry Faulds in his 1912 book Dactylography, or the Study of Finger-prints. Faulds describes the case of a man with no identification documents, apparently killed by an oncoming train, whose badly damaged body was fingerprinted and later identified when the post-
mortem fingerprints matched an antemortem fingerprint record on file at New Scotland Yard.

In the United States, the U.S. Armed Forces is credited with the early recognition and use of fingerprints as a means to identify the dead. Harris Hawthorne Wilder and Bert Wentworth in the book Personal Identification, published in 1918, describe the case of a body floating in the Hudson River near Fort Lee, New Jersey. Visual identification was impossible because of
the condition of the remains; however, the victim's clothing led investigators to believe that the man was in the military. As a result, postmortem fingerprints were recorded and forwarded to the War Department, which ultimately matched the recovered prints to an antemortem record on file
in Washington, D.C.

Wentworth and Wilder also describe the creation of military dog tags containing an etched recording of a soldier's right index impression for the purpose of identifying war dead.

The creation of military identification tags containing fingerprints corresponded with the U.S. entry into World War I (WWI). While no detailed account exists regarding the use of fingerprints to identify U.S. war dead from WWI, there are documented cases involving the use of fingerprints for casualty identification. One such instance concerns the sinking of the S Tuscania in 1918. The Tuscania was transporting American troops to Europe when it was torpedoed by a German U-boat, killing approximately two hundred of the twenty-two hundred soldiers onboard. Because of the swirling seas and rocky coastline off the Scottish island of Islay, many of the recovered bodies were damaged beyond recognition, but could be identified through the use of fingerprints.

From WWI onward, fingerprints have played a principal role in U.S. military victim identification efforts.
While law enforcement initially adopted fingerprints as a means of criminal identification, their use for victim identification also became important.
One of the first FBI identification cases occurred in 1925 when the Portland Police Bureau submitted fingerprints of a decapitated corpse, recovered from the Columbia River in Oregon, to the FBI for identification purposes.

When compared to fingerprint records in the national repository, the FBI was able to establish the identity of the body, providing a crucial lead in the open criminal investigation. Eventually, the use of fingerprints for human identification evolved into one of the primary tools used today by law enforcement, medicolegal professionals, and disaster mortuary response teams for personal identification. This expanded civil application of fingerprints was initiated by the FBI, which in 1940 recognized the need for the scientific determination of identity in mass fatality incidents. As a result, the FBI Disaster Squad, a worldwide response team that assists with disaster victim identification efforts through fingerprints, was established. This Disaster Victim Identification (DVI) team has responded to more than 225 disasters since its inception in 1940, identifying over half of the recovered remains the team has examined through fingerprint analysis.

 

1.3 Fingerprint Fundamentals
The term fingerprint is used to describe a reproduction of the friction ridge arrangement present on the tips of the fingers when an impression is deposited on a touched surface. This arrangement of the friction ridge skin is permanent due to the underlying structure of the skin and unique because of complex physiological events, both genetic and environmental, that occur during fetal development. Friction ridge skin is present on the palmar and plantar surfaces of the hands and feet. As such, impressions from the fingers and palms of the hands as well as the toes and soles of the feet can all be used for personal identification purposes.

The friction ridge skin found on the hands and feet differs from the relatively smooth skin that covers the rest of the human body. This corrugated skin, consisting of raised ridges and recessed furrows, assists individuals with grasping objects and gaining traction. Friction skin is composed of two main layers, an outer layer called the epidermis and an inner layer cal led the dermis. The epidermis has five different cell layers, whereas the dermis is one large layer consisting mainly of connective tissue and blood vessels.
The epidermal ridges are supported by double rows of papillae pegs on the dermis, which can play an instrumental role in the recovery of fingerprints from deteriorating bodies.

Detailed examination of the friction ridge skin also reveals that ridge path, in most instances, is not continuous across the entire surface of a finger.
Some ridges, called ending ridges, will flow and abruptly come to an end, while other ridges, called dividing ridges or bifurcations, will flow and separate into two separate and distinct ridges. Additionally, some ridges are as long as they are wide and are called dots. These ridge events are commonly referred to as characteristics or minutiae, and their spatial relationship to one another in a friction ridge impression is the basis for fingerprint comparison and identification. Other features existing in a fingerprint called formations are ridge path deviations involving the combination of one or more ridge characteristics. Further examination of the friction ridge skin also reveals irregular ridge contours and sweat pores. Structural and dimensional elements of ridges and pores, when clarity permits, can be used in conjunction with ridge characteristics for comparing and identifying fingerprints.
Friction ridge arrangement at the ends of the fingers generally forms pattern types referred to as loops, arches, and whorls. For classification purposes, these basic pattern types can be further divided into eight distinct subgroups based on observed differences within patterns of the same type. Approximately 65% of all fingerprint patterns are loops, 30% are whorls, and 5% are arches. In a loop, the friction ridges enter from one side of the pattern, recurve, and pass out or tend to pass out the same side the ridges entered. An arch has ridges that enter from one side of the pattern, make a wave in the middle, and pass out the opposite side from which they entered. In a whorl, the friction ridges tend to have a circular or spiral ridge flow. It is important for an examiner to note the ridge flow of a print for orientation purposes and the recognition of focal areas that will ultimately assist in the identification process. While pattern configuration alone cannot be used for individualization, it can be used for exclusionary decisions made by an examiner.
Fingerprints fall into three categories: latent, known, and plastic impressions. A latent fingerprint is the two-dimensional reproduction of the friction ridges of the finger on an object by means of perspiration, oils, or other contaminants that coat the surface of the ridges when a finger touches an item. These types of prints generally must be made visible through the use of forensic technology such as alternate light sources, chemical techniques, or fingerprint powders. In some instances, latent prints can be visualized without the use of any fingerprint processing techniques and are called patent prints.
Latent impressions are deposited by chance and are usually fragmentary in nature with varying degrees of quality. Alternatively, a known fingerprint is the intentional reproduction of the friction ridges of the finger onto a fingerprint card or appropriate contrasting surface. A known exemplar can be recorded using a number of standard techniques, to include black printer's ink, inkless/chemical methods, and LiveScan, which is a computer-based system that creates digital fingerprint images by scanning the fingers. Finally, a plastic print is an impression left in a malleable substrate, such as wax or putty, which retains an image of the friction ridge arrangement.

 

1.4 Comparison and Identification of Friction Ridge Impressions
While the terminology used to describe the fingerprint identification process has varied over the years, the basic methodology employed by forensic examiners has remained relatively unchanged. One aspect that has changed, however, is an increased awareness of the underlying scientific basis for fingerprint identification. This change has resulted in the standardization of he identification process based on the extensive research of former Royal Canadian Mounted Police Staff Sergeant David R. Ashbaugh, which centers around a quantitative-qualitative philosophy to fingerprint examination called ridgeology. Ridgeology is a holistic approach that focuses on the biological uniqueness of friction ridges and involves the sequential examination f the features and spatial relationship of ridges, noting the quality and quantity of the assessed information for identification purposes.
This examination is conducted using a methodology that incorporates sound scientific protocols and practices, allowing for accurate and repeatable conclusions that meet rigorous scientific standards. The standard methodology used by fingerprint experts to conduct friction ridge examinations is called ACE-V, for analysis, comparison, evaluation, and verification, which are the four fundamental phases utilized in this process.
Analysis focuses on the examination of the quantity and quality of information present in a print, which can be broken down into three levels of detail.
Level 1 detail refers to the overall ridge flow and pattern type of a print. Level 2 detail refers to ridge path, which corresponds to the spatial relationship of ridges and their characteristics in a print. Level 3 detail refers to individual ridge attributes, which involve ridge shapes and pore structure/location in a print. The fingerprint examiner must consider various quality factors, such s distortion, that could alter the reliability of the observed information when determining the suitability of a print for comparison purposes. The information present in the latent or poorest quality print is always examined first, followed by examination of the known or best quality print.
Comparison of friction ridge impressions is a side-by-side assessment of the information analyzed in both prints. The latent or poorest quality print is compared to the known or best quality print to minimize cognitive bias. The examiner first assesses the level 1 information from the analysis of the latent print and compares this with the information gathered from the analysis of the known print. If the information matches, the examiner then assesses the level 2 information from the analysis of the latent print and compares it with the information gathered from the analysis of the known print. Comparison is not a simple "point counting" exercise; in fact, there is no scientific basis for a minimum point threshold or specific number of characteristics that must match in two prints for an identification decision to be reached by an examiner.
Level 3 information is usually noted when assessing level 2 detail and, if visible, is compared as well. These comparative measurements begin at a focal point selected by the examiner and progress through the ridges of the entire print in series. For this information to match, the ridge path, of sufficient quantity and clarity, must have the same unit relationship and relative position in both prints. When a fingerprint examiner determines that the information present in a latent and known print is in agreement, with no unexplainable dissimilarities, an identification decision can be reached. Due to the pliability of the friction skin, and other environmental factors, friction
ridge impressions of the same finger will never look exactly alike.
Evaluation involves rendering a decision based on the results of the analysis and comparison phases of the identification process. There are three possible conclusions that can be reached by an examiner as defined by the Scientific Working Group on Friction Ridge Analysis Study and Technology (SWGFAST).* The first conclusion is individualization (identification) and involves the determination that sufficient information present in two impressions matches, meaning that they are from the same source. The second conclusion is exclusion and is the determination that the information present in two impressions does not match, meaning that they are not from the same source. The third conclusion is an inconclusive decision and is the determination that a conclusive comparison cannot be reached because of a lack of quality or absence of a comparable area in the known exemplar.
Verification is the final step in the ACE-V methodology. Although verification is not technically part of the identification process, it serves as a form of peer review, ensuring reliable and accurate results. All individualizations made by a fingerprint expert are verified, through an independent examination of the identified prints, by a second qualified latent print examiner as quality assurance mechanism. Verification of exclusion or inconclusive decisions also can be performed but is not required by SWGFAST. Under certain circumstances, the FBI uses a more rigorous form of peer review called blind verification, where the verifying examiner is unaware of the evaluation decision reached by the original fingerprint specialist prior to conducting his or her examination.
There are two basic premises that form the foundation of the friction ridge identification process and allow for the use of fingerprints as a means of individualization. These premises concern the individuality and persistency of the friction skin, which have been scientifically validated over time through academic research and the work of experts in the field of fingerprints.

Individuality refers to the fact that fingerprints are unique; no two areas of friction ridge skin are the same, not even on identical twins. The basis for this statement rests in human embryology and genetics, beginning during fetal development. The physiology of friction ridge skin begins with the development of the volar pads, which are protuberances of tissue that begin to form on the tips of the fingers at about the eighth week of gestation. The degree of complexity of the volar pads (their size, shape, and location on the finger) greatly influences ridge flow or level 1 detail.
These volar pads regress or are absorbed back into the finger at about the tenth or eleventh week of gestation, when friction ridges begin to form. Primary ridges develop first, followed by secondary ridge development or the occurrence of furrows between the papillary ridges. Although most of this activity has a genetic component, a nearly infinite number of environmental factors result in the random development (differential growth) of friction ridges and their corresponding level 2 and 3 detail. The end result of these genetic and environ mental variances during friction ridge formation is complete biological uniqueness, down to the structure of a single ridge.
Persistency refers to the fact that friction ridges are permanent and remain constant throughout a person's lifetime, until decomposition after death, unless otherwise affected by accidental injury or intentional mutilation. The basis for this statement rests in human anatomy and the histology f the skin. As the body sloughs off dead skin cells, they are replaced by new skin cells generated from the bottom or basal layer of the epidermis.

The cells joined together through cell junctions are replaced the same way for an entire lifetime unless scarring occurs. Thus, the basal layer acts as an immutable root system that is the foundation for the permanency of friction ridges and their corresponding level 1, 2, and 3 detail.

 

1.5 The Postmortem Fingerprint Recovery Process
It has been said by some in the forensic community that there is little difference between obtaining fingerprints from the living and the dead. Those in the fingerprint profession involved with victim identification understand that recovering quality friction ridge impressions from human remains can be one of the most challenging tasks that an examiner can perform. This ask differs markedly from printing the living on many levels and requires both mental composure and physical dexterity on the part of the forensic examiner for successful completion.
While fingerprints are obtained from both the living and the dead for identification purposes, the reasoning and mind-set behind the action are different.
For example, most examiners can recall the first time they examined human remains, whereas very few can recall with any certainty the first time they finger printed the living. The psychological aspects of working with the dead, especially in mass fatality situations, are being addressed by many organizations involved with forensic identification operations throughout the world.
Some techniques used to assist examiners in overcoming stresses associated with human identification include mandatory leave, favored by European organizations, and debriefing sessions, favored by U.S. agencies, to include the FBI.
The technical aspects of fingerprinting the living and dead might appear similar on the surface, but in most cases they are considerably different. The majority of identification specialists will record fingerprint impressions from living persons electronically using LiveScan technology or by lightly coating the fingers of an individual with black printer's ink and recording the inked impressions onto a fingerprint card. If the individual has an injury to the friction ridge skin (cut/laceration), an examiner can wait for the skin to heal and record the impressions at a later date. When fingerprinting the deceased, recovered bodies often will exhibit environmental damage to the friction ridge skin, which will contribute to the decomposition/deterioration of the skin and will never heal. In these instances, bodies should be examined promptly and the friction skin reconditioned or returned to a near natural state before quality prints can be recorded.
The examination of human remains is often complex; accordingly, the author has developed a deceased processing methodology to assist forensic examiners in the successful and expedient recovery of postmortem impressions to confirm or establish identity. This three-step process involves:
1. Inspecting and cleansing the friction skin
2. Reconditioning compromised friction ridge skin
3. Recording postmortem impressions

 

1.5.1 Inspecting and Cleansing the Friction Skin
The first step in processing deceased individuals is visually inspecting the hands to determine if the friction ridge skin has been damaged. In order for the examiner to make this determination, the hands must be cleansed of any contaminant (dirt, blood, etc.) using a sponge and warm, soapy water.
A soft toothbrush can be used for removing foreign matter adhering to the fingers, but the examiner must proceed carefully to preserve the integrity of the friction ridge skin. If the friction skin is not compromised, the hands are cleansed and postmortem impressions are recorded. If the friction skin is damaged, the examiner should note the type of damage that has occurred because this will assist in choosing the correct reconditioning technique.
The location and nature of the deadly event will offer a good indication of the type of damage observed by an examiner.

 

1.5.2 Reconditioning Compromised Friction Ridge Skin 

Surrently, the literature on processing techniques used to successfully recover fingerprints from distressed bodies is often limited and dated. The following discussion includes a modern array of reconditioning techniques designed to assist forensic examiners in the recovery of quality postmortem impressions from damaged friction ridge skin. To simplify this task, the techniques are organized according to the types of damage most often encountered in the examination of human remains. Although medicolegal professionals routinely obtain postmortem fingerprints in death investigations, it is recommended that they seek assistance from a qualified fingerprint examiner when using reconditioning techniques to avoid the possibility of rendering the friction skin unprintable.
One of the most prevalent types of friction skin damage involves maceration and decomposition of human remains related to prolonged water/moisture exposure. This type of damage manifests itself in the creation of creases or wrinkles in the fingers as well as the deterioration of the epidermal layer of friction ridge skin. The primary concern with water-soaked remains is the elimination of wrinkles from the friction skin in order to obtain suitable postmortem impressions. The examiner can pinch/stretch the skin in an attempt to remove the creases or inject tissue builder, a viscous liquid used for embalming purposes, into the fingertips. Tissue builder is injected into the end of the finger by passing the needle through the first joint or medial phalange, resulting in the elevation of depressed areas in the fingertip, thus removing any wrinkles that are present.

The initial stages of decomposition may result in a phenomenon known as gloving, in which the epidermal layer of skin separates from the dermal layer of skin. In this situation, the epidermal skin can be cut from the dermis, dried, and placed over the protected finger of an examiner for recording purposes. If the epidermal layer is completely separated from the dermal layer, ecordings of the epidermis and dermis should be taken to ensure that they match and are not from different individuals. This is especially important in disaster situations where a commingling of remains often occurs. In an advanced state of decomposition, the epidermis has usually putrefied, leaving exposed dermal skin. Forensic examiners should not be surprised if they inspect a body and see little or no visible friction ridge detail, as it is often a sign of exposed dermal skin. Recovered dermal prints will appear different than epidermal prints because a dermal impression will have a double row of dermal papillae representing a single epidermal ridge.
Fingerprints can still be recovered from putrefied remains by using the boiling technique, a method that uses boiling water to visualize or elevate ridge detail on the dermis through osmotic rehydration. This process involves bringing water to a boil in a hot pot and then submerging the hand from the body into the water for five to ten seconds. The hand is then removed from the water and examined for friction ridge detail, which will be visible on the surface of the dermis if it has been successfully reconditioned.
If no detail is present, the hand can be placed back into the water for another five to ten seconds. When there is abrasion trauma to the skin, an alternate form of the procedure should be used where the water from the hot pot is indirectly applied to the hand, such as with a sponge, to control development and avoid increasing the size of any cuts that may obscure visible friction ridge detail.

Desiccated or mummified remains are one of the most difficult and time-consuming types of friction skin damage to recondition. Because the body tissue dehydrates and shrinks, often resulting from exposure to arid conditions, the friction skin becomes unusually rigid with severe wrinkling.
The body also may display signs of rigor mortis, which must be overcome to successfully examine the remains. In order to break mild rigor, an examiner can forcefully straighten or flatten the fingers of the hand. If this does not work, the examiner can cut the tendon on the inside of the fingers to release the rigor and allow the fingers to straighten. Cases of extreme rigor, such as those involving desiccated remains, require the removal of the fingers from the hand. In order to remove items (digits, clothing, etc.) from a body, permission must first be granted by the medical examiner or coroner. After approval is granted, the examiner may amputate the fingers and place them into sealable jars labeled with the corresponding finger position.
Hands associated with desiccated remains must be rehydrated in order to remove the wrinkles from the friction ridge skin. This is usually accomplished by soaking the fingers in jars containing dishwashing liquid diluted with warm water. Alternatively, a number of different chemical methods can be used to rehydrate the skin, such as soaking the fingers in 1 to 3% sodium hydroxide or in the leather conditioner Lexol® (Summit Industries, Inc., Marietta, Georgia). The rehydration of the fingers may take hours or days, depending on the extent of desiccation. Accordingly, the examiner should regularly check for skin pliability. When the skin has softened, the fingers are removed from the jars and washed clean. The examiner should try to tretch the skin to remove any creases and then use tissue builder to remove any remaining wrinkles, returning the fingers to a near natural appearance.
If friction ridge detail is not visible or the fingers have become saturated from soaking, the boiling technique can be used after rehydration to visualize any ridge detail that may be present.
The examination of charred remains can be a delicate task. This type of damage results in brittle friction skin that can be further damaged through excessive handling of the body. When an individual is burned to death, the body will usually exhibit clenched hands. Clenching of the hands is a natural reaction that tends to protect the friction ridge detail on the fingers and possible residual prints left by the victim. Instead of forcing the fingers open, the tendon on the inside of the fingers should be cut and the fingers gently straightened. It may also be necessary to remove the fingers from the hand for examination. At this point, photography is advised to capture any ridge detail that may be present on the fingers. Hardened and loose friction skin ay be twisted off the finger, while epidermal skin that has lifted off the dermis but is still attached to the hand should be removed using forceps and curved Metzenbaum scissors for recording purposes.
After the skin has been removed, it should be rinsed with warm water and, if wrinkled, carefully flattened out prior to printing. If the epidermal ridges are unprintable, the underside of the epidermis can, in some instances, be used for recording purposes. Recovered prints from the underside of the epidermis, however, will be in reverse color and position.
This means that ridge color and ridge flow of the recorded print will be the reverse image of the ridge color and ridge flow of the prints contained on the antemortem standard. In cases of extreme charring with no visible friction ridge detail, the boiling technique can be used as a last resort to clean off the hand and possibly raise ridge detail on the fingers.

 

1.5.3 Recording Postmortem Impressions
Before attempting to record quality impressions from the friction skin, the examiner must ensure that the skin is dry. This can be a simple procedure that involves blotting the hands dry with paper or cloth towels, or in some instances, where moisture has penetrated deep into the tissue, more intensive techniques may be required. One such technique involves the use of isopropyl alcohol to dry water-soaked friction ridge skin. Isopropyl alcohol is applied to the hands, which are then blotted dry with paper or cloth towels. This process should be repeated until the desired results are achieved. Another technique involves using a hair dryer to dry the skin by setting the hair dryer on low heat and blow drying the hands. The final method, called the flame technique, involves the use of a butane grill lighter to dry the skin. The flame is moved back and forth across the friction skin for a few seconds, taking care to dry but not to char the skin. The same results can be accomplished by rolling a finger over a hot light bulb instead of using an open flame.

Since the early days of fingerprinting, the standard method for recording fingerprints has been the application of a thin layer of black printer's ink to the fingers and then recording the friction ridge impressions onto a fingerprint card. Although this technique works well with the living, it is more difficult in its application for printing the dead. The examination of a body usually takes place with the deceased positioned on his or her back for eventual autopsy. This position makes it difficult or nearly impossible for the examiner to apply ink to the fingers using an inking plate, and thus requires that ink be rolled onto a spatula and applied to the fingers. The application of
too much ink may result in distorting/smudging of the recorded prints. It is also not feasible to roll the finger impressions onto a fingerprint card, especially when rigor mortis has set in the body. The recording of inked impressions is thus accomplished using a tool called a spoon that can be placed on the end of the finger. Fingerprint blocks are held in the spoon and are used to capture friction ridge detail and create a complete fingerprint record.
The recommended recording strategy for recovering fingerprint impressions from deceased individuals involves the use of black powder and white adhesive lifters. This technique is quick and easy to use, resulting in clear prints compared with those obtained through inking. The first step in the procedure is to lightly coat the fingers with black powder, covering the entire pattern area, using a traditional squirrel hair fingerprint brush or sponge-type paintbrush.
Each finger is powdered separately and placed on an adhesive lifter, such as Handiprint (product of CSI Forensic Supply), that is cut to the approximate size of the finger blocks on a fingerprint card. The lifter is placed just below the first joint and then wrapped around the fingertip to record the powder impression. If debris from the finger is being lifted along with the powder and obscures ridge detail, a less adhesive lifter, such as a mail label, should be used.
The recorded impression is then affixed to the back of an acetate fingerprint card. This type of clear plastic card can be produced by photocopying a standard fingerprint card onto transparency film.
Some alternative printing strategies that are useful in recording quality postmortem impressions from difficult remains involve the use of Mikrosil® (Kjell Carlsson Innovation, Sundbyberg, Sweden) and AccuTrans® (Ultronics, Inc., Cuyahoga Falls, Ohio). Mikrosil is a casting putty that was originally developed for toolmark examinations before being used in the fingerprint discipline to recover latent impressions from irregular surfaces. AccuTrans is a relatively new polyvinylsiloxaine casting agent specifically designed for the recovery of latent fingerprints and other forensic evidence. Both products have also been used as a way of recording friction ridge impressions from the living and the dead. The casting technique works exceptionally well on desiccated remains containing wrinkles in the friction skin. This technique can be used after the fingers have been rehydrated or at a disaster scene when rehydration is not an option and fingerprints need to be recovered from remains without delay. The first step is to lightly coat the fingers with black powder, followed by the application of Mikrosil or AccuTrans, which is white in color, to the fingers. Mikrosil must first be mixed and then applied to the fingers with a spatula, whereas AccuTrans comes with an automix gun option that allows direct application to the fingers. The casting material must be allowed to dry on the fingers before being peeled off to capture the print. Recovered prints will be in correct position and color when compared to an antemortem standard.
When all described recording techniques have failed to produce quality postmortem impressions, images of the friction ridge detail present on the fingers can be captured with digital photography. The proper selection of direct, oblique, reflected, or transmitted lighting schemes will enhance the appearance of ridge detail, often resulting in quality images that can be used
for identification purposes. It is also important to capture 1:1 images of the friction skin because the photographs will be compared with antemortem impressions of natural size. If this cannot be accomplished, a scale or object of a known size should be included in the photograph so that image dimensions can be corrected through the use of digital imaging software.

 

1.6 Automated Fingerprint Identification Technology
While the recovery of identifiable postmortem impressions from human remains is an integral part of the forensic identification process, it is imperative that these impressions be compared with an antemortem standard in order to have any value in establishing or verifying human identity. The expeditious identification of postmortem remains depends on the most important
technological advancement in the history of fingerprinting: the Automated Fingerprint Identification System. This computer system, known as AFIS, has evolved from its early use as a means of searching criminal ten-print records to its use today in identifying suspects of crimes through latent print searches against local, state, and national fingerprint repositories.
In 1999, the FBI released the Integrated Automated Fingerprint Identification System (IAFIS), which consists of a biometric database of millions of fingerprint cards and criminal history records submitted by law enforcement agencies around the country. IAFIS allows the FBI and other criminal justice agencies to electronically access the national fingerprint repository in
Clarksburg, West Virginia, for ten-print and latent print searches, meaning that criminals can be tracked by their fingerprints throughout the United States. If individuals have been arrested, it is probable that their fingerprint records are contained in the FBI Criminal Master File (CMF). If individuals have been fingerprinted as part of a background investigation for a job or for military service, it is likely that their fingerprint records are contained in the FBI Civil File (CVL).
Some of the most important criteria in using fingerprints as a means of human identification is the cost-effective and rapid reporting of results, which is directly related to fingerprint computer technology. AFIS, in addition to being a crime-fighting tool, is also instrumental in the identification of the dead. If a dog tag or wallet can be obtained from decedents, the fingerprint record can be located by entering personal identifying information from these items into AFIS and printing off the antemortem record if it exists.
The postmortem prints then can be compared manually to the antemortem record to verify identity. In instances of closed-population disaster situations, meaning that the identities of individuals killed in the event are readily known, personal identifying information can be obtained from items such as an airline manifest and entered into AFIS to retrieve fingerprint records.
The records can be obtained and manually compared with recovered postmortem impressions, depending on the number of fatalities. Larger disasters often will preclude quick manual comparison of antemortem records, which means that postmortem prints must be searched electronically through AFIS. Postmortem prints are first scanned into AFIS and encoded, meaning that the friction ridge minutiae or characteristics are digitized. Criteria such as pattern type and finger position are then selected followed by the launch of the fingerprint search. Searches of postmortem impressions can take only a few minutes, depending on the submitted criteria, and result in a list of candidates with the closest correlation to the submitted print. Although the I in AFIS represents identification, the comparison of the candidates and any dentification decision, as it relates to latent print examination, is made by a certified fingerprint examiner and not the computer.
The FBI has portable IAFIS terminals that can be deployed to disaster scenes around the world with the capability of searching recovered postmortem impressions through remote access to the national fingerprint repository.
In open-population disasters, meaning that the identities of individuals killed in the event are not readily known, recovered postmortem prints should be searched through an automated fingerprint system for identification purposes.

This is best addressed by a practical look at the deployment of AFIS and the use of fingerprints for mass fatality victim identification in the aftermath of the 2004 South Asian Tsunami in Thailand. Over five thousand people were killed when tsunami waves struck the coast of Thailand on December 26, 2004. Because Thailand is a popular vacation destination, the dead ncluded not only local residents but also many tourists, particularly from Scandinavian countries. The magnitude of the disaster resulted in a worldwide request for antemortem identification records for those believed killed in the catastrophe. As a result, AFIS was established to assist in the massive identification effort because no automated fingerprint system existed in Thailand. Fingerprint cards submitted by various government agencies, as well as latent prints developed on items believed to have been handled by the deceased, were entered into AFIS and used as antemortem standards.
Identifiable postmortem fingerprints, recovered from the majority of the bodies using the boiling technique, were then searched against the available antemortem database, resulting in numerous identifications.
An important issue discovered in Thailand when using an automated fingerprint system for victim identification involved dimensional variations associated with recovered postmortem impressions. In some instances, the friction skin will expand or shrink to a point that the abnormal size of the recovered prints must be addressed by the examiner in order for a correlation to be made with an antemortem record in AFIS. The lack of antemortem fingerprint records, especially in developing countries, and the ability to recover quality postmortem impressions can limit the effectiveness of fingerprints in identifying the dead.

 

1.7 Conclusion
Fingerprint identification is arguably the oldest forensic discipline known to man.
Fingerprints have proved over time to be the most rapid, reliable, and cost-effective means by which to identify unknown deceased individuals, especially in a mass disaster setting. Through the use of various postmortem finger print recovery techniques, skilled fingerprint examiners can recover friction ridge impressions even from the most decomposed bodies. The recovered prints can be manually compared with known antemortem records or searched through an automated fingerprint system (AFIS) in order to verify or establish identity. The identification of remains through fingerprints accomplishes the most important and difficult mission of the forensic identification operation: the timely and accurate notification of families regarding the fate of their loved ones.

 

Acknowledgments
Special thanks goes to Carl Adrian of the FBI Special Projects Unit for his assistance in the preparation of Figure 6.2. I am also thankful for the patience and support of my wife, Lori, and beautiful daughter, Avery, from whom I draw inspiration and without whom I would be at a loss for words.

 

References
1. Galton, F. 1892. Finger prints. London: Macmillan & Co.
2. Herschel, W.J. 1916. The origin of finger-printing. London: Oxford University Press.
3. Beavan, C. 2001. Fingerprints: The origins of crime detection and the murder case that launched forensic science. New York: Hyperion.
4. Henry, E.R. 1922. Classification and uses of finger prints. 5th ed. London: H.M. Stationary Office.
5. Bridges, B.C. 1948. Practical fingerprinting. New York: Funk & Wagnalls Co.
6. Faulds, H. 1912. Dactylography, or the study of finger-prints. London: Halifax, Milner & Co.
7. Wilder, H.H., and B. Wentworth. 1918. Personal identification. Boston: The Gorham Press.
8. Schwartz, S. 2006. SS Tuscania, an American history. http://www.renton.50megs.com/Tuscania/Rememberance/Intro.html.
9. Browne, D.G., and Brock A. 1954. Fingerprints: Fifty years of scientific crime detection. New York: E.P. Dutton & Co.
10. Ashbaugh, D.R. 1999. Quantitative-qualitative friction ridge analysis: An introduction to basic and advanced ridgeology. Boca Raton, FL: CRC Press LLC.
11. Symposium Report. 1995. Israel National Police: International Symposium on Fingerprint Detection and Identification. J. For. Ident. 45:578-84.
12. Wertheim, K., and A. Maceo. 2002. The critical stage of friction ridge and pattern formation. J. For. Ident. 52:35-85.
13. Uhle, A.J., and R.L. Leas. 2007. The boiling technique: A method for obtaining quality postmortem impressions from deteriorating friction ridge skin. J. For. Ident. 57:358-69.

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