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Fuming With Super Glue
The preferred fuming method now involves Super Glue. Yes, that's a trademarked product, and to start with that specific product was what we used. Since then, other products have been developed that work similarly, but most of the time, when a fingerprint technician says Super Glue, s/he means Super Glue. The glue is put onto a hard, nonflammable surface, and the item to be fumed is put near it. Then both are sealed into an airtight container. The prints, thick white in color, develop naturally in about forty-eight hours.
If more speed is needed, there are several methods of accelerating the process. One involves putting cotton balls soaked in sodium hydroxide near the Super Glue; another involves heating the Super Glue to about 200° Fahrenheit; and a third involves substituting a gel called Hard Evidence —a cyanoacrylate ester in a reusable sealed pouch—for the Super Glue. All have their advantages and disadvantages. Not only is Super Glue less pleasant to smell than fat pine, but also its use in this manner—which is not what the manufacturer recommends —can produce highly toxic fumes.
But it works on some extremely difficult surfaces. Probably there is no surface more difficult to fingerprint than a thin plastic bag, and Constable Garry Birch of Perth, Western Australia, was once faced with the task of printing 1,800 plastic bags that had been collected in a major drug raid. After some consideration, Birch acquired a large wooden crate used for overseas shipping. He then suspended the bags on strings draped across the container. He bought ninety-six tubes of glue and squeezed the glue onto three strips of aluminum foil, which he put on the bottom of the container. He then sealed the container for seventy-two hours.
Suspecting that much glue might have produced fumes nobody wanted to smell, he asked the fire department to open the container while using full breathing apparatus. After the fumes had dissipated, he examined the bags and found fingerprints on thirty of them.
Seventy-two hours may seem like a long time to wait for results. But if Birch had tried to dust with magnetic powder or photocopier toner, the only other reliable means of getting prints from thin plastic bags, he'd probably have spent a lot more time and might well have gotten worse results.
Technicians Steve Rowley and Bob Braman, in Salt Lake City, once Super Glue-fumed an entire airplane. Another technician, telling me about it, emphasized, "It wasn't a real airplane; it was only a Piper Cub." I assured him that I consider a Piper Cub a real airplane—especially for this purpose.
Lasers and X Rays
Less common methods of looking for latents include lasers and soft-tissue X rays. The FBI first used lasers in examining for prints on highly difficult items, such as the inside of powdered rubber gloves (yes, that's what I mean: the gloves were coated inside with powder before wearing) and the sticky side of tape, in 1980. In that year alone, they located 215 prints by that method, which led to forty-five convictions.
The Tokyo Police Department pioneered in the use of soft-tissue X ray to get fingerprints of a perp from the skin of a victim. This complicated method is still not available to most police departments because of the narrow time window in which such prints can be obtained and the lack of equipment; in fact, I am not familiar with any department that routinely uses this method. But that does not mean that your super P.I. can't use it.
More common—though still quite rare—means of getting prints from the victim's skin involve either thin silver plates or unexposed, developed, fixed, high-gloss, resin-coated photographic paper. Remember that as recently as twenty years ago, technicians believed that it was impossible to get prints from the victim's skin— although the materials with which this work is now done were already available.
Latents From Human Skin
Thin silver plates are given an extremely high polish using jeweler's rouge; the photographic print paper is cut into usable sizes, and then both are used approximately the same way. Both require several factors:
1. The victim's skin containing the print must be relatively dry and hairless. Hairy areas or moist, sweaty areas will not hold prints. Usually the only areas meeting this description are breast or abdomen skin or the inside of the wrist and upper arm.
2. The perp's hands must have been fairly moist, and must have well-developed ridges.
3. Minimal time must have passed. Twelve hours is about the absolute maximum if there is to be any chance of success.
The silver plate or the photographic paper is clapped down firmly, in one motion, on the victim's skin where s/he remembers having been touched. It is lifted off—again in one firm motion—and carefully dusted. In the case of the photographic paper, the developed latent is then covered with tape. However, this procedure produces the mirror image of a print lifted in the normal manner.
The silver plate is used the same way. When the print is transferred to a lifting card, it will produce a mirror image of a normal print. In order to work with either comfortably, you will need to make a photographic negative and then an internegative and then use the internegative the way you would normally use a fingerprint lift. See Figure 4-5 for an explanation.
In general, photographic paper is just as efficient and is far cheaper and easier to work with. According to the Tokyo Police Department, the soft tissue X ray provides better results. Unfortunately, as I said, it simply is not generally available in the United States. Your supercop can use it if s/he wants to.
Where to Look for Prints
Ident people spend a lot of time watching the way people use their hands. Notice, next time you are writing, the way your palm and little finger curl into a reverse C—or into a C, if you're left-handed— and rest on the paper. Those are the parts of the hand that leave prints on a forged check. Next time you start to drive an unfamiliar car, notice how you automatically adjust the rearview mirror. That's the best place to find prints in a stolen car—not the steering wheel,
on which the prints pile up on top of each other until they're totally illegible.
Figure 4-6 gives the names of the parts of the hands. The thenar zone and the hypothenar zone turn up most often on documents, especially on the backs of checks. The palmar zone, which is divided into several numbered areas for ease in discussion, turns up when something has been grasped. The thumb and the first three fingers turn up on opposite sides of something that has been grasped with the fingers rather than with the whole hand. The little finger almost never is found in crime scenes.
The interpalmar zones show up in various situations; again, the best way to figure out where to look for what, is the same way ident people do it: Watch the way people use their hands. If you are trying to decide for fiction what part of the hand would leave prints, actually put your hands through the actions your fictitious perp would have used. (This is done very well on "Murder, She Wrote." I've enjoyed watching Angela Lansbury twisting her hands around, regarding them with wide-mouthed and wide-eyed calculation.)
Hew Do You Know What You've Found?
I told you I knew that print on what turned out to be Leon McCoy's revolver was a thumb print as soon as I saw it. How did I know? How do you work with those prints from crime scenes?
We need another chapter for that.
TABLE 4_
The Latent Fingerprint
These pages come from The Finger Print Manual, published by Sirchie FingerPrint Laboratories, Inc., and are used by permission. The charts have been edited for use in this publication.
Latent fingerprints generally consist of a mixture of natural secretions from glands in the skin. Often these latent prints contain contaminants that are picked up on the skin (some fingerprints consist solely of contaminants).
Determination of the major constituents of a fingerprint by simple visual examination is usually impossible, unless the fingerprint is in an obvious contaminant (blood, grease, dust, etc.).
Distribution of the major constituents of secretions of the sweat glands and the actual distribution within a given latent fingerprint vary from donor to donor, and can greatly vary with the s
ame donor at any given time (large variations occurring from day to day and even minute to minute).
Sweat Gland Secretion
There are three major sweat glands found in the human body: the eccrine glands, the sebaceous glands and the apocrine glands. The secretions of these glands are as follows:
Most natural fingerprints consist of a mixture of sebaceous and ec-crine sweat. Some of these chemicals persist for long periods of time in latent fingerprints while others may decompose, evaporate or diffuse.
The presence of a specific chemical in a fingerprint depends on the constituents of the original fingerprint, the nature of the surface, the time elapsed since deposition, and the storage conditions. Factors such as temperature, exposure to light and water and the relative humidity affect the chemical and physical nature of a fingerprint.
Water is the first component to be lost from most fingerprints. Because of this, when dealing with prints more than a few days old, processes which primarily detect water are less effective than those processes which detect primarily the fatty component.
Detection of Latent Fingerprint Constituents
Some fingerprint detection processes are specific to particular chemicals, while others detect the oily or greasy physical nature of the surface.
Since the chemical and physical nature of a fingerprint is generally not known before the fingerprint examination, the techniques used and the order in which they are applied are determined primarily by the particular surface type the fingerprints are on.
Methods for Latent Fingerprint Development
Powders: Many powders for the development of latent fingerprints are available. With fresh fingerprints, the aqueous component of the fingerprint contributes significantly to the adhesion of powders, while with older prints, powders adhere principally to the fatty deposits of sebaceous sweat. In many cases, flake powders such as Silver Latent Print Powder are more sensitive than other types of powder. In some instances, a less sensitive powder may be more effective.
Fluorescence examination: Some of the natural constituents and some types of environmental contamination found in latent prints will fluoresce under ultraviolet illumination. Treatments are available that cause fingerprints to fluoresce more strongly. Also, some types of fingerprints can be enhanced by using ultraviolet illumination that is absorbed by the fingerprint that excites the fluorescence of the background. (Ninhydrin-developed fingerprints are an example of this.)
Iodine: This technique is very simple to use. Iodine vapor is absorbed by latent fingerprint deposits (along with some reaction to unsaturated fats contained in the fingerprint) forming a brown image. The developed print should then be fixed to avoid any possible fading.
Ninhydrin: Ninhydrin is a general-purpose fingerprint reagent for paper and other porous surfaces. It reacts with amino acids in fingerprints. An intermediate colored image varying from orange to purple (depending on donor and conditions) is produced. With full development, the compound Ruhemann's Purple is produced. Full development can take several days, but the reaction can be accelerated by heating and humidification.
Silver nitrate: Silver nitrate can be used on raw wood surfaces. (Ninhydrin is preferred for use on paper.) Silver nitrate reacts with the chlorides contained in latent fingerprints producing silver chloride, which when exposed to light turns a dark gray.
Small particle reagent: This process is quick and simple. Small particle reagent is a suspension of fine molybdenum disulfide particles. Small particle reagent adheres to the fatty constituents of latent fingerprints to form a gray deposit. The developed print can be lifted to simplify photography.
Cyanoacrylate (Super Glue): Cyanoacrylate vapor develops fingerprints on a wide range of surfaces. The cyanoacrylate vapor produces a white deposit as a result of polymerization with the latent fingerprint. Water acts as a catalyst for this polymerization. Smooth, nonporous: This includes such surfaces as glass, paint, varnish and hard plastic moldings. (Metals are not included.) Powders can be used effectively on most of these surfaces. Fluorescence examination, small particle reagent and cyanoacrylate can also be used on these surfaces.
Rough, nonporous: Rough or grained plastic moldings are examples of this surface type. These surfaces are generally unsuitable for effective use of powders; therefore, more success can generally be expected with small particle reagent and cyanoacrylate fuming.
Paper and cardboard: Paper and cardboard (including plaster board) that has not been waxed or plastic coated should be treated with ninhydrin. Powders may be used on smooth surfaces prior to treatment with ninhydrin, but powders are generally insensitive to older fingerprints.
Plastic packaging material: This includes such surfaces as polyethylene, polypropylene, cellulose acetate and laminated paper. Small particle reagent, cyanoacrylate and powders may be used, small particle reagent being very effective in many cases.
Soft vinyl (PVC), rubber and leather: Simulated leather and cling film are examples of these surface types. Small particle reagent, cyanoacrylate and powders may be used on these surfaces.
Metal (untreated): This applies to bare metal surfaces, not surfaces that have been painted or lacquered. Small particle reagent, applicable powder types and cyanoacrylate can be used on this type of surface.
Raw wood (untreated): Bare wooden surfaces that have not been painted or treated should be treated with ninhydrin. Smooth wood may be treated with powders, while silver nitrate may be used on light woods.
Wax and waxed surfaces: Articles made of wax (such as candles) and paper, cardboard and wood that have been coated with wax can be treated by nonmetallic powders and cyanoacrylate.
That was written in 1934. But even I can remember a time when it was essential to get a set of fingerprints from Georgia to Washington, D.C., in a matter of hours. We—the police officers and the FBI—ran all over town until the FBI managed to locate somebody who had a fax machine. I had to make separate 8 x 10 photo enlargements of each of the ten fingerprints, which took about two hours. It took about ten minutes per enlargement to fax them—almost another two hours. That was less than twenty years ago. Now, almost every police department has a fax machine, and the card itself could be faxed in less than twenty seconds.
But what are fingerprints? Where did the idea come from?
A Brief History of Fingerprinting
The first mention of fingerprints in Western fiction came, about the same time, on both sides of the Atlantic: in stories by Mark Twain (Life on the Mississippi) and Arthur Conan Doyle ("The Adventure of the Norwood Builder"). The first recorded use of fingerprints that has been found so far—and we don't know whether it was for identification or for magic—came in a Babylonian text of about four thousand years ago, when several army deserters were recaptured and compelled to leave the marks of their fingers and thumbs. Although it would be more logical to assume that this was for some sort of magical purpose, the presence in archaeological excavations of well-designed magnifying lenses makes it at least possible that prints were being used for identification.
We're on surer ground by the time we get to China, about two thousand years ago: People were using their thumb marks as seals, and captured river pirates a thousand years ago were compelled both in fact and in fiction to provide ink prints of their thumbs. This thousand-year continuity provides strong evidence that the prints were being used for identification. Japan also has a strong history of the use of thumbprints as personal signatures and seals.
Fingerprints were first used in a criminal case in Rome in the time of the Caesars, although the size and shape of the prints were in question rather than the ridge detail. A senator was found murdered. His young second wife, hysterical, pointed to the bloody handprints on the wall near the murder, insisting that her blind stepson had committed the murder and then had to fumble his way from the body. The Praetorian Guard arrested the youth, who maintained his innocence. In court, his defense attorney was able to prove that the handprints were much too small to fit the young man
, and that in fact the wife had committed the murder and deliberately made the prints in order to direct suspicion toward her husband's son from his first marriage.
The first known Western movement toward the use of fingerprints for identification occurred in Germany, in 1788, when J.C.A. Mayer stated that the skin ridges in two or more individuals are never identical. In 1856, also in Germany, Herman Welcker made a print of his right palm and stored it away. In 1897, he repeated the print and studied the two carefully, determining that there were no changes. Prior to that, in 1823, Professor Johannes E. Purkinje classified fingerprints, but he seems not to have realized that the prints were unchangeable and never identical from individual to individual.
Things came together at the end of the nineteenth century with the work of William Herschel in India, Henry Faulds in Japan, and
Francis Galton in England in 1892. Although Herschel and Faulds both noticed the individuality of fingerprints and used them for identification purposes, it was Galton who proposed a practical system of classification and filing. Sir Edward Richard Henry in 1899 and 1900 modified and improved upon Galton's system, enabling it to handle much larger files than Galton ever envisioned. Henry's system is still in use today in all of the English-speaking world and many other countries.
At virtually the same time, in 1891 in Argentina, Juan Vucetich was producing a system of fingerprint classification that is in use in most Spanish-speaking countries. Vucetich made the first known use of real fingerprints in a criminal investigation of the case of a woman who murdered her illegitimate children and tried to place the blame on her estranged boyfriend, who was not the father of the children. People who have used both the Vucetich system and the Henry system maintain that for anyone starting from scratch, the Vucetich system is far easier to learn. However, the Henry system is too deeply ingrained in most of the rest of the world to be easily changed now.