I asked Dr. Hildebrand that, considering all of the shoe manufacturers out there, from top-of-the-line footwear to cheap sneakers, how can an expert determine which brand of shoe left the mark? Or is it just a matter of matching patterns found at the scene with shoes in the possession of a suspect?
“There are a few methods,” he says. “There are computerized databases6 on the market where a footwear impression from a crime scene can be searched through to determine its brand or model. There are some examiners that have trained themselves to recognize various logo and or trademarks to determine the brand name.”
Do footwear specialists typically visit crime scenes? Dr. Hildebrand says no. “Normally a footwear expert will not go to a crime scene. Crime scene investigators are trained to properly document, collect and preserve footwear evidence in all forms. The footwear specalist performs the examination and comparison between the crime scene print and the suspect’s shoes.”
He does point out, however, that, “there are many examiners trained in gait patterns recognition,” who might be called to a crime scene and could possibly provide assistance with our zombie case. This, however, is unlikely to happen in the first few hours of a case.
According to technology sales representative Daniel Conklin, there is also highly specialized hardware and software systems for analyzing the collected evidence. “Many departments—at least the bigger labs and some of the private labs—have something like the Raman spectrometer, which can provide valuable ‘fingerprints’ for comparing and differentiating footwear materials.7 Raman spectroscopy using the Foram685-2, is fast, non-destructive, can be performed on materials in situ and requires minimal operator training—an ideal technique for the examination of forensic evidence.”
The Zombie Factor
Matching footwear impressions to a zombie who is later captured or killed is not hugely important. Determining the identity of the zombie, especially of patient zero, is.
If the manhunt lasts more than a day, an expert in walking patterns may be called in. A zombie walks with a distinctive shuffling gait. That will leave equally distinctive footprints on the ground. Zombies are also indifferent to hiding their tracks, which means that they’ll walk over (rather than around) anything in their path, including mud, puddles, dust, and other surfaces that will take a useful impression. In the absence of K-9 trackers, the foot impression expert can often assist the police in identifying the attacker’s gait and provide useful details for officers to track that person.
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Tracking the Undead Predator
Though K-9 trackers wouldn’t need to rely on footprint evidence, human trackers would. The tread patterns of shoes or the shape of bare feet are distinctive enough to the trained eye.
The skill of tracking is not something a person can usefully learn from a book. It requires a good coach as well as good senses, acute observation, concentration, patience, perseverance, alertness, physical fitness, a good memory, an analytical mind, an understanding of nature, intuition, and a creative imagination.
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JUST THE FACTS
Dactylosocopy—The Science of Fingerprinting
Fingerprinting is one of the oldest reliable methods of identification. Fingerprints have been used for thousands of years as a method of identification. The ancient Chinese used prints as signatures as early as the thirteenth century. In 1685 anatomist Marcello Malpighi of the University of Bologne identified the patterns found in fingerprints, describing them as loops, whorls, and ridges—terms still used today. In 1858 a British civil servant, Sir William Herschel, began requiring residents of Bengal, India, to use handprints for identification; and many years later discovered that the patterns of palm and fingerprints did not change as people aged. In 1880, Henry Faulds, a physician practicing in Tokyo, determined that fingerprints were unique enough to be used as positive identification of individuals. It was a fairly short step from that to the 1892 publication of Sir Francis Galton’s book Finger Prints, which became a landmark textbook on the subject, and in which Galton reinforced Malpighi’s use of whorls and grooves as unique identifiers. Nine years later Sir Edward Henry created a classification system based on five distinct types of prints—a system that informed the fingerprinting identification methods still used in Great Britain and the United States.
Perhaps the most significant landmark, though, was the 1910 trial of Thomas Jennings who became the first person in the United States to be convicted of a crime based on fingerprint evidence. Even when appealed, the guilty verdict was upheld based on the overwhelming evidence that fingerprints are unique.
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Fingerprint Card by Jonathan Maberry
“Even zombies were human once. There’s a very good chance of identifying the zombie through fingerprints, which could aid police in tracking the plague back to its start.”
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Expert Witness
According to fingerprint expert and forensic author Elizabeth Becka,8 “The number of comparisons between fingerprints has increased exponentially and we still haven’t found two the same. They’re unique to the individual because they develop at random. They don’t change throughout one’s lifetime. Sand them down, they’ll just grow back in the same pattern.”
George Schiro, MS, consulting forensic scientist, tells us, “The uniqueness of fingerprints is a hypothesis that can never be proven, since we could never fingerprint and compare all people, living and dead, to determine if individual fingerprints are unique. Based on the embryonic development of fingerprints and the studies showing that identical twins have different fingerprints, it is highly unlikely that two fingerprints would be identical, but there is an extremely small probability that two fingerprints could randomly match. Given the context of a crime, the next question to ask is how many people had access to the crime scene. Based on the relatively small number of people that had access to the scene, and given the extremely small probability that two fingerprints could match randomly, then the fingerprints within that small, defined population would be unique.”
I asked why there was so much fuss built around fingerprints, and Schiro said, “The most important thing to know about fingerprints is that the courts have upheld the uniqueness of fingerprints. Fingerprinting is also the least expensive and best means of human identification. Information from a fingerprint can be quantified and digitized, prints can be placed in a database and searched. And the most important things to know about fingerprint evidence collection are that print collection at a crime scene should be a top priority, and the surface on which friction ridge prints have been deposited should be tested with a known print, prior to attempting to lift the evidentiary print. Prints might have to be photographed prior to a lift attempt. The crime scene investigator should also know how to develop latent (invisible) prints using a variety of techniques from a variety of surfaces. All relevant areas should be examined for latent and patent (visible) prints. Finally, other evidence at the crime scene must not be ignored.”
He warns us, however, “Whether or not a surface takes a print depends on numerous factors, including the type of surface. Just because a person touches a surface, it doesn’t necessarily mean that an identifiable print can be recovered from that surface. Typically, rough or textured surfaces can take a print, but an identifiable print may or may not be recovered from that surface. Other factors can determine whether or not an identifiable print is left on a surface. These factors include, but are not limited to, the following: the physiology of the individual, the activity of the individual prior to touching the surface, the humidity, the temperature, the absorbance of the surface, the pressure used in touching the surface, movement of the finger while touching the surface, whether or not there is an intervening material between the surface and the finger, and the cleanliness of the fingers.”
Becka agrees. “Whether or not you find a fingerprint on an item depends on the amount of oil and water on the person’s hands, the item’s surface, the climate, a
nd about a million other things. Contrary to TV, you don’t always find prints on this or that and you don’t ever find prints on this or that.”
Even so, science marches on and there have been several significant advances in fingerprinting over the last few decades. According to Becka, “The biggest advance is, of course, computerized database searching. I can mark the points of minutia in a latent print collected at the scene and the computer finds possible matches for me. This means I don’t have to search card files for matching prints and die of tedium. Note that the computer does not decide if someone is a match or not, it only summons the prints with the most similar pattern of points.”
One point of clarification: fingerprint is used somewhat loosely here—as it is in all pop culture. According to Martin Leadbetter, FFS RFP BA (Hons), international fingerprint expert and chairman of The Fingerprint Society, “‘Fingerprint’ is usually used to describe inked impressions taken for a specific use, e.g., recording prisoners’ fingerprints, elimination fingerprints, cadavers etc. The terms, latent, latent mark (or mark, as used in the UK) always refers to impressions found at crime scenes or on forensic exhibits.” He goes on to explain the different kinds of prints:
Rolled ten-print impression (U.S. and international terminology) sometimes referred to as inked impressions or inked fingerprints in the United Kingdom: This is an impression whereby ink has been placed onto the ridged skin of the fingertip and then subsequently rolled onto a ten-print card or form in order to record an exact image of the finger’s pattern and ridge detail. Upon the arrest of a suspected person, this procedure is repeated for each of the ten digits in order to produce a ten-print card.
Slap prints (or in the United Kingdom, plain impressions): Slap prints are also recorded on the ten-print card and are used to check that each of the rolled ten-prints has been taken in the correct order. The four fingers of each hand are inked by being placed flat on an inked surface and then placed simultaneously onto the ten-print card. The two thumbs are dealt with in the same manner. (As a general rule, the term slap prints is not used in the United Kingdom.)
Palm prints: These are inked impressions recorded the same as ten-prints.
Latent palm marks, palm marks: These are palm marks recovered from crime scenes or forensic exhibits.
As technology increases, the reliability of fingerprints also increases. “The data sharing between computer databases holding vast collections of fingerprints has only increased the realization that fingerprints remain totally unique,” he says. “With the rapid searching of fingerprint databases no instance of two impressions taken from different fingers, thumbs or palms have been recorded. All claims within academia and the media that fingerprints are unreliable or unsafe are purely unsubstantiated and in some instances, mischievous. It should also be remembered that when referring to fingerprints the same criteria also belong to palms, toes and soles. Furthermore, all 187 species of primate possess fingerprints and share the same pattern types with humans. All instances where it has been reported that ‘two people have the same fingerprints’ or an error in identification has occurred are the result of poor forensic work or worse, conspiracy to pervert the course of justice.”
According to Leadbetter, different people need to know different things about fingerprints. “If you are a juror, then you need total confidence in the fingerprint system of identification, its uniqueness and the integrity of the fingerprint experts. If you are a detective you will know that fingerprint evidence, provided it leads to useful evidence, is the very best evidence you can ever hope for. The overriding issue here, is that fingerprint evidence, due to its unrivalled uniqueness is still the most conclusive and infallible of all the forensic sciences.”
This need for unique perspective holds true for the process of fingerprint collection. “Jurors would need to have confidence in the scene examiner, as indeed would all the officers of the court,” says Leadbetter. “For the scene examiner it’s a matter of knowing where logically to look and to find those fingerprints which will later assist in proving guilt.”
Leadbetter tells of another recent development that is helping police in the United Kingdom and America: “There is also Live-scan. This is a process whereby arrestee’s finger and palm prints are recorded electronically without the need for ink and paper. Once recorded, Live-scanned prints may be sent electronically to the computer system. As Live-scan devices have built-in ‘aliveness’ sensors it would be intriguing to know whether prints could actually be captured from zombies.” And, he adds, “It is also possible to retrieve DNA from latent prints, although again this would not be possible from all latents due to the factors previously mentioned.”
Forensic consulting scientist George Schiro tells of another new technology on the rise: touch evidence. “DNA recovered from touched evidence has a great impact on the development and collection techniques associated with latent prints. In the past, if a smudged print was developed, then that smudge had no value. Today if a smudge is developed, this smudge could be swabbed using a sterile cotton swab and a solvent, usually sterile water, deionized water, or an ethanol solution. This swab can then be air dried and eventually analyzed for a DNA profile. Also, surfaces such as rough or textured surfaces, typically not as good for recovering identifiable prints are better suited for recovering identifiable DNA profiles. Of course, in collecting this DNA evidence, crime scene investigators must take added measures to reduce the potential of DNA cross contamination between samples collected.”
The Zombie Factor
On the topic of zombie fingerprints, Schiro says, “A person who had only recently died then became reanimated would probably leave an oil based print for only a few hours after death. After that, the oils would probably not be replenished and the skin would dry out. An investigator would be better off looking for prints based in something the zombie had touched (blood, body fat, etc.) prior to touching the surface. If the corpse has been dead for a while or is reanimated in an advanced state of decomposition, then it is highly unlikely that usable prints would be recovered.”
Zombies, whatever else they are, were people first. A large percentage of our population has had identifying information recorded. If our patient zero had ever been convicted of a crime, then his prints would be on record. Just as they would if he had been in the military, worked for any of the more highly classified organizations, been part of certain drug testing programs, been a government employee, held a driver’s license in certain states (such as in California, Georgia, etc.), been registered with any of the child-tracking services, and so on. Bottom line is that there are a lot of people registered in the various law enforcement and military fingerprint databases. Though not all of these databases are shared,9 there is enough information out there that a hit from a collected print is fairly likely.
Beeka believes that this would help us find our zombie, providing he’s one of the millions who have been printed. “Prints are not deleted, usually, from a database if the person dies, so a dead person’s prints would most likely still be in the file. And if they indulge in gore a lot, they’d be leaving plenty of prints in blood.”
Schiro has a lot of confidence in the growing database of prints, and says, “Fingerprinting would most likely be helpful in identifying the living dead who were reanimated shortly after their death for two major reasons. The first is that the recently deceased would be less likely to have their prints removed from the AFIS system, if indeed their prints are even in the AFIS system. Only a small percentage of the population is actually in the AFIS system and this small percentage is comprised mostly of people who have been arrested and booked into jail. The second reason is that those zombies reanimated shortly after death would be more likely to leave behind an identifiable print.”
“The human body decomposes at varying speeds depending upon a myriad of factors,” Leadbetter says. “For example…is the body inside or outside? Is the temperature high or low? What is the humidity? Is it immersed in water? Has it been bu
rnt? Has it been subject to any contaminants? How did it die? Is it skinny or obese? Now in zomboid terms this raises a very interesting question. Bearing in mind that the skin on the hands and feet is often the last part of the human tissue to decompose, it must really be asked how quickly did the zombie regain its undeadness? If this was fairly soon after natural death, it could be that hardly any fingerprint detail had decomposed. If however it was the reverse, then there may not be any detail at all. In either scenario, the factors listed above will have to be considered.”
Schiro concurs: “And what about a zombie in an advanced state of decomposition? That would complicate things.” According to Schiro: “At some point decompositional changes will render fingerprint analysis useless. How the decompositional changes affect the fingers depends on many factors including the environment the body was exposed to prior to reanimation. Bodies exposed to the environment are going to decompose at a more rapid rate than bodies that have been embalmed or refrigerated. Bodies found in water are going to decompose differently than bodies not found in water. Insect and animal activity on bodies exposed to the elements could also affect fingerprints. Depending on the environmental conditions, the extremities (fingers and toes) could dry out and wrinkle, rendering them useless for leaving behind identifiable prints. Bodies undergoing decompositional changes in water or in humid environments will tend to slough off the outer layers of skin. This would also make it difficult to recover prints from touched surfaces.”