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Fingerprints & Palm Prints Friction ridge skin. Mark Twain & Fingerprints.
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Mark Twain & Fingerprints • Mark Twain's 1883 memoir, "Life on the Mississippi", described how a murderer was identified by fingerprints. In a later book, "Pudd'n Head Wilson" - 1893, he described a dramatic court trial that included a fingerprint identification. • Twain demonstrated more than a superficial understanding of fingerprints and how to match them AND an understanding of the value of physical evidence: • He thought that jumping to conclusions about the probative value of evidence may not be correct. • In fact he was among the first to write about fingerprints and their value in solving crimes
On June 24, 1895 Mark Twain was interviewed by a reporter from the Elmira Advertiser concerning a bloody hand print found at the scene of a murder . “Elmira, N.Y., June 23. - Mark Twain was found at Quarry farm today, where he is resting quietly preparatory to taking his lecture tour around the world. He was asked what he thought of the hand-print found at the Henry house and what similarity it bore to the bloody hand mystery solved by Pudd’n-Head Wilson. He said he had not read the latest phases of the Henry murder, but when shown the account in a newspaper of finding a bloody handprint on the basement door he said: "They seem to be in doubt as to which of the two made that hand-print, the assassin or the murdered man. I should think that would be easy to determine. They have a man under arrest whom they suspect, as I understand it, and I should think they could easily get a hand-print from him and compare it with the bloody hand-print and then determine whether he made it or not. There is nothing in this case that you or I can suggest that would not suggest itself to anybody's mind. Thus far that hand-print has not a value, because it is not determinable whose it is. You don't know whether it is valuable until you know that it is not the hand of the dead man. If it is the hand of a survivor it can have some value. "If it is clear that hand-print, so the marking of the ball of the thumb, for instance, is distinct and can be followed, there can be a print taken from that and then enlarged by a pantographer ten or twenty times, so that there is no mistaking these lines, because they are clearly defined. Then unquestionably they can take as many thumb marks corresponding with those until they find the man that left that hand-print there. That is sure. When a thumb mark is magnified the difference in the lines can be easily detected between ten or twenty thumbs--that is, you can find as many innocent people as you please in that way, but there is only one guilty. There is only one thumb in the world that will correspond with the print that that man left there. When they have found the man who made that thumb print they will know him sure without any question at all, and there will be no need of an expert to determine whose hand made the print. "When you have got that far you have not arrived at any goal yet. It will be pretty strong evidence, but there is a suggestion that there could have been several persons there and you want to know who it was that killed the man. But whether he is guilty or not you won't know. It if were known that there were no persons present but the assassin and the victim you know you have got the assassin. It is well worth while to follow that clue if they can find that the dead man did not leave that print there. If that body is not decomposed it will be an easy matter to find out whether he made the hand-print or not. If he did not, that narrows the murder down considerably. I do not say that the bloody hand-print can convict anybody, but it can help. It will be remembered that in 'Pudd’n-Head Wilson' it was proved the bloody finger prints on the dagger were not left there by the accused person in court, but were made by a person in court, but not accused."”[1]
Three Basic Patterns • Loop • Right slant • Left Slant • Whorl (most complex) • Plain • Central Pocket Loop • Accidental • Double Loop • Arch • Plain • Tented
Recurve • Core • Delta
A Whorl pattern • Two or more deltas. • Deltas and the areas between them must be recorded. Delta Delta
Arch – no delta or core. Must be fully recorded in order to distinguish its individual characteristics. Tented Arch
Minutiae - Substructure • Identification – exclusive to one person • Elements • Ridge patterns: Loops, whorls, arches • Identifying characteristics—Minutiae • An ID occurs when a sufficient number of identifying characteristics are the same for the suspect print and the known print
Concerning Fingerprinting at Past Crime Scenes • Should there have been more successes? • Could more criminals have been apprehended? • Should more usable prints been developed and were all the probative prints that could have been found and developed actually developed? • How many prints at those crimes were treated improperly? • How many unsuccessful attempts were there, AND how could the development attempts employed been successful?
Intelligently Employing New Methods • The responsibility of the team leader or Laboratory scientist is to preserve the original print detail as it was left at the scene. • Using new or novel techniques without employing a scientific approach is incorrect • Employing new methods • Understanding the underlying science, • Doing an in-depth validation, and • Without being blind proficiency tested - is risky. • Using the scientific method • Forging ahead without appropriate knowledge, training, validation and proficiency testing enhances the possibility of destroying evidence.
A Reasoned, Scientific Approach • Fingerprint development has a long history, an evolution in scientific terms. • Scientists and investigators have spent decades devising methods to develop and enhance fingerprints at scenes and in latent print laboratories. • Menu of methods. • For the practicing scene investigator, new methods seem complex. • They increasingly employ sophisticated chemical, immunological, physical and imaging technologies. • The Goal is to define a chemical mechanism that will react with the fingerprint residue for all surface types – Mission Impossible
On-Scene Printing Menu-driven Vs Logic-Based • Fingerprint paradigm is menu-driven • Designed for non-scientists to know when to employ methods in order to minimize errors. • Merits born from a wealth of experience and success • Criminals apprehended and successfully prosecuted. • Success certainly speaks loudly, • An important flip side to that argument.
Field-forward Fingerprint Development Is it Necessary? • Fingerprint development methods are mostly laboratory-based, many have on-scene applications. • Reasons for developing/enhancing prints in the field, best course of action depends on the dynamics of the investigation, the location of the prints and the surface on which the prints lie. • The decision to process prints on-scene, however, should be determined by scene related constraints. • There is the natural temptation to develop as many as possible at the scene, but the reasons for processing there should make sense only in the context of the investigation.
Where to Develop a Print At the Scene OR in the Laboratory
On-Scene Scene Decisions • Surface, resources, environment, age of the print, amount and quality of print residue present, scene scientist/investigator knowledge, experience, technology and its limitations are among the most important. Dusting is the most common choice, believed to be the best, easiest and quickest way to obtain results. For a given circumstance, that may, in fact, be true. • Dusting blindly is wrong. Minimum Considerations
Scene considerations • Surface on which prints lie, the • Environment at the scene, and the • Age of the print (length of time) it was in that environment.
Surface • Existing Paradigm considers surfaces as porous, non-porous or semi-porous. • These are simplistic because other considerations are not often spelled out. • Surfaces affect print development decisions. • How protected: Painted, and if so, is the paint matte, semi-gloss, gloss or is it one of the newer finishes that has texture? • Texture: How detailed ; smooth, lightly textured, heavily textured? Depth. • Porosity: Is the surface and or the paint porous, non-porous or semi-porous? • Color: Is it dark, light or somewhere in-between
Surface • Print development paradigm is surface driven. • Porous surfaces have a preferred, menu-driven group of methods as do the • Non-porous of which dusting is but one approach
Methods • Investigators prefer methods with which they are the comfortable, • Dusting - nonporous surfaces. • Have a reluctance to embrace new technology. • Unfamiliarity with newer techniques, • skepticism concerning how well they perform versus those in their comfort zone, and • insecurity about the underlying science are probably other reasons. • Also, newer techniques are more complex and require more rigorously controlled conditions.
Tools/Resources • Surface is the first step in the decision process of finding, developing and preserving fingerprints at the scene. • Surface nuances • What is the best way to enhance fingerprints on cornered surfaces • How to print on textured surfaces • What methods are applicable ? • Physical, • Chemical • Imaging technology • Topography • Photography, lifting and preservation • Involve sets of decisions that must be made.
Environmental Conditions Age of the Print • The environment and the length of time a print had been exposed to that environment should affect decisions concerning a print development strategy - heat, humidity, pollution, UV radiation, dust and time - affect print quality. • It is important to understand why and how the environment plays • a critical role in the integrity of the fingerprint residue because it • can dictate which method has the best chance of success. • Examples • If hot and humid and the surface is one of those discussed above, dusting or superglue fuming may have the best chance of success. • If the temperature is moderate, 50o F, and the humidity is between 20 and 90%, the same may be true. • If it is winter and the humidity is low and the house overheated, the print could be dry (dehydrated print residue) and unresponsive to traditional dusting or even superglue fuming.
Scene Logic Essential skills Innate or born from knowledge and experience. • Finding Prints: Involves a myriad of skills – • Refers to the intellectual ingredients • Locate, develop, lift, archive fingerprints • An intellectual exercise • Best technology does not guarantee success. • Only formula for success • Understanding • Scene environment • Nature of the crime
Knowledge of the Science • Simply knowing how to investigate crime scenes, employing critical • thinking and using logic is not enough to guarantee success. • The missing ingredients • Knowing which techniques are available for developing fingerprints • Understanding how they work in specific circumstances. • Knowing and understanding the dynamics of crime scene investigation are • Uunderstandinghow evidence “talks” and why this translates into knowing the likely location of evidence, e.g., fingerprints. • An open window at a burglary scene should attract attention. • Maybe it was already open, but other evidence such as footprints in the dirt outside the window or the dry residue prints on the floor under the window might raise its importance up a notch. • Areas where a struggle took place may lead to fingerprints on objects or on the floor. • Other signs might lead to places or objects a perpetrator touched: • A weapon on the floor, a smashed lamp, a knife, a fork, drinking vessels, door jams and windows at entrance and egress points, etc.
Experience • Experienced scene scientists/investigators are better at developing and finding prints than a novice or a student. • Experience also rules when it comes to employing science and using technology. • Understanding the science • Experience with it • Critical.
Critical Thinking • Assessing and digesting information the scene presents and then distilling it so That probative evidence pops out and speaks. • It’s a language that criminalists and experienced investigators understand. • An open window unrelated, but developed fingerprints on the windowsill will be irrelevant. (why develop them in the first place) • The area of a struggle will say that someone fell onto the floor and that there might be usable prints there. • Bloodstains on the floor in the kitchen might be significant. Check for ridge detail. • Eating utensils might have prints that can be important. • Other bloodstains in the kitchen may be irrelevant, if they occurred because the deceased suffered a lacerated finger while chopping onions – check the body for recent finger wounds (the ME might decide this is a defensive wound). • A partially chopped onion on the cutting board, some of it mixed with a drop of blood, and a bloody knife lying on the floor should scream “No relevance.” • A bloodstain out of context from other blood at the scene should also scream: “Perp injured.” Certainly the blood itself is a critical piece of evidence, but it is likely not the only evidence in that area.
Out-of-the-Box Reasoning • An extension of critical thinking. • A way of thinking that translates into an investigative strategy leading directly to the most probative evidence. • Ability to marry seemingly unrelated information to form a hypothesis of what happened or where to find evidence. • Such thinking involves more than experience. It’s a mind that works on a different level, one that creates order from chaos. • These individuals “see” evidentiary links and how they fit together. • Others can use their experience to approximate it. • The illustration of the “lone, out-of-place” bloodstain. It is a gift.
Environment Age of the Print • The environment and the time print exposed to that environment should affect print development strategy – heat, humidity, pollution, UV radiation, dust and time - affect print quality. • Environment plays a critical role in the integrity of the fingerprint residue because it can dictate which method has the best chance of success. • Examples • If hot and humid and the surface is one of those discussed above, dusting or superglue fuming may have the best chance of success. • If the temperature is moderate, 50o F, and the humidity is between 20 and 90%,th e same may be true. • If it is winter and the humidity is low and the house overheated, the print could be dry (dehydrated print residue) and unresponsive to traditional dusting or even superglue fuming.
