Read Ebook: The Science of Fingerprints: Classification and Uses by United States Federal Bureau Of Investigation Hoover J Edgar John Edgar Contributor

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Generally speaking, in the course of their work fingerprint operators find it necessary to take the impressions of three classes of deceased persons.

They are:

- Those who have died recently, in which cases the task is relatively simple.

- Those dead for a longer period, in which cases difficulty is experienced due to pronounced stiffening of the fingers, the early stages of decomposition, or both.

- Those cases in which extreme difficulty is encountered because of maceration, desiccation, or advanced decay of the skin.

These problems will be considered separately.

When the fingers are flexible it is often possible to secure inked fingerprint impressions of a deceased person through the regular inking process on a standard fingerprint card. Experience has proved that this task can be made easier if the deceased is laid face down and palms down on a table .

In all cases where inked impressions are to be made, care should be exercised to see that the fingers are clean and dry before inking. If necessary, wash the digits with soap and water and dry thoroughly.

In the event difficulty is encountered in trying to procure fingerprints by the regular method, it may prove more convenient to cut the 10 "squares" numbered for the rolled impressions from a fingerprint card. After the finger is inked, the square is rolled around the finger without letting it slip. Extreme caution should be exercised to see that each square bears the correct fingerprint impression. After all the inked impressions are properly taken, the ten squares bearing the impressions are pasted or stapled to a standard fingerprint card in their proper positions, i.e., right thumb, right index, right middle, etc. Whenever possible the "plain" or "simultaneous" impressions should also be taken.

In some cases it will be found necessary to obtain or improvise a tool similar to a broad-bladed putty knife or spatula to be used as an inking instrument. The ink is rolled evenly and thinly on the knife or spatula and applied to the finger by passing the inked knife or spatula around it. The tool, of course, replaces the usual glass inking slab or plate, the use of which is extremely difficult or awkward when printing a deceased person.

This second group consists of cases in which the hands of the deceased are clenched, or the finger tips are wrinkled, or decomposition has begun, and/or where there are combinations of these three conditions. Cases of this sort may necessitate cutting off the skin. Legal authority is necessary before cutting a corpse. Such authority may be granted by state law or by an official having authority to grant such a right.

In cases where rigor mortis has set in and the fingers are tightly clenched, the fingers may be forcibly straightened by "breaking the rigor." This is done by holding the hand of the deceased person firmly with one hand, grasping the finger to be straightened with the four fingers of the other hand and placing the thumb, which is used as a lever, on the knuckle of the finger and forcing it straight . The inking tool and "squares," as previously explained, are then used to secure the fingerprint.

In the event the rigor cannot be completely overcome, it will be most helpful to improvise or secure a spoon-shaped tool for holding the cut squares or cut strips while printing the fingers, similar to the tool mentioned briefly in the discussion of crippled fingers. This tool, somewhat resembling a gouge without the sharp edge, should have a handle, a concave end, and a frame or clamp to hold the cardboard squares or strips. In Figure 390, one type of tool is illustrated. This tool eliminates the necessity of rolling the deceased's finger, since the "square" assumes the concave shape of the tool, and the gentle pressure applied to the inked finger when it is brought in contact with the square results in a "rolled" impression without actually rolling the finger.

Another problem encountered in this second group includes cases in which the tips of the fingers are fairly pliable and intact, yet due to the presence of wrinkles in the skin, complete impressions cannot be obtained. This condition can be corrected by the injection of a tissue builder, procurable from a dealer in undertaker's supplies. If this is not available, glycerin or water may be used.

The method is simple. Injection of the tissue builder, glycerin, or water, is accomplished by the use of a hypodermic syringe. The hypodermic needle is injected at the joint of the finger up into the tip of the finger, care being used to keep the needle below the skin surface . The solution is injected until the finger "bulbs" are rounded out, after which they are inked and printed.

Occasionally, in stubborn cases, entry of the needle at the joint and injection of the fluid will not completely fill the finger bulb. It may be necessary, therefore, to inject the fluid at other points of the finger such as the extreme tip or sides, until suitable results are achieved . The tissue builder has a distinct advantage over glycerin or water, inasmuch as the builder hardens after a short time and is not lost, whereas glycerin and water sometimes seep out when pressure is applied in printing. To offset seepage at the point where the hypodermic needle is injected, whenever possible, tie a piece of string tightly around the finger just above the point of entry of the needle.

When the tissue builder is purchased, a solvent for cleaning the hypodermic syringe and needle should be acquired, inasmuch as the builder will harden in the syringe and needle.

Those cases in which decomposition in its early stage is present belong in this group also. Frequently, the outer layer of skin has begun to peel from the fingers. A careful examination should be made to determine if the peeling skin is intact or if a part of it has been lost. If the skin is in one piece, an effort should be made to secure prints just as though it were attached normally to the finger. Or, if it is deemed advisable, the skin may be peeled off in one piece, placed over the finger of the operator, and inked and printed as though it were his own finger.

Occasionally the first layer of skin is missing. There remains the dermis or second layer of skin which is also of value for identification purposes. This second layer would be dealt with as though it were the outside skin, using the techniques described above. The ridge detail of the second layer of skin is less pronounced than that of the outer skin, however, and more attention and care are needed in order to obtain suitable impressions.

So far this discussion has dealt with the taking of impressions of fingers when the flesh is fairly firm and the ridge detail intact. A different problem arises when the fingers are in various stages of decay. The techniques of treating the fingers in such cases vary greatly, depending upon the condition of the fingers with respect to decomposition, desiccation, or maceration.

In cases involving badly decomposed bodies the first thing to do is to examine the fingers to see if all are present. If they are not, an effort should be made to determine whether the missing finger or fingers or even a hand was amputated during the person's lifetime, or whether the loss was due to other causes such as destruction by animal or marine life. Deductions from this examination should be noted on the fingerprint record. This point is made in view of the fact that in the fingerprint files of the FBI and some police departments, the fingerprint cards reflecting amputations are filed separately. Noting amputations may lessen to a great extent a search through the fingerprint files.

In making the initial examination, attention should be given to the removal of dirt, silt, grease and other foreign matter from the fingers. Soap and water are good cleansing agents. So is xylene, a chemical which will readily clean grease and fatty matter from the fingers. Good results can be achieved by utilizing a child's soft-bristled toothbrush in cases where the skin is fairly firm. The brushing should be done lightly and the strokes should follow the ridge design in order to clean not only the ridges but the depressions as well. In the event that the skin is not firm enough to use the toothbrush, a cotton swab may be used. The fingers should be wiped very lightly with either soap and water or xylene, always following the ridge contours.

At this point the fingers are again examined to determine the condition they are in, based upon the circumstances in which the body was found. Study and actual experience have shown that there are three general types of conditions to be considered: Decomposition or putrefaction, prevalent in bodies found in brush or buried in earth; desiccation or mummification , noted in bodies which have been found in the open in dry protected places, or bodies subjected to severe heat; and the group involving maceration , which ordinarily results from being immersed in water.

The degree of decomposition, desiccation, or maceration varies from a comparatively early stage to an extremely advanced stage. Accordingly, each case must be considered individually. For example, what is done successfully in one case of desiccation may not show favorable results in another. Hence, the techniques outlined below point out generally what can be done, and has been done, with success.

When a body is found, the hands usually will be tightly clenched. The first problem will be to straighten the fingers. If rigor mortis has set in and an effort to straighten the fingers as previously explained fails, the difficulty can be overcome easily. Using a scalpel, make a deep cut at the second joint on the inner side of each of the four fingers. They can now be straightened with the application of force . The thumb, if it is cramped or bent, can generally be straightened by making a deep cut between the thumb and the index finger. These incisions are made for the obvious purpose of examining the fingers to determine if there is any ridge detail. Before this fact can be definitely ascertained it may be necessary to cleanse the pattern areas with soap and water or xylene, as previously explained.

If the case is one involving decomposition, the operator is confronted with the problem of dealing with flesh which is rotted or putrefied. The flesh may be soft or flabby and very fragile. If this is so, an examination is made of the finger tips to see if the outer skin is present. If the outer skin is present and intact, it may be possible, using extreme care, to ink and print in the regular manner. Sometimes, the outer skin, although present, will be too soft and fragile to ink and roll in the regular way. In such cases, when the ridge detail is discernible, the skin, if it is easily removed from the finger, or the finger itself may be cut off at the second joint and placed in a 10- to 15-percent solution of formaldehyde for approximately an hour to harden it. Skin placed in a formaldehyde solution usually turns a grayish white and becomes firm. However, it will be brittle and may split if not handled carefully. The skin is placed in the solution only until it hardens sufficiently, after which it is removed and carefully wiped dry with a piece of cloth. Then the skin, placed over the operator's own thumb or index finger and held in place by his other hand, is inked and rolled as though the operator were printing his own finger. If a legible print is not obtainable in this manner, the operator should examine the underside of the skin.

In many instances, where the ridge detail on the outer surface has been destroyed or is not discernible, the ridge detail is clearly visible on the underside . If this is the case, the skin is inverted very carefully to prevent splitting or breaking and then is inked and printed in the usual way. It must be borne in mind, however, that when the underside of the skin is printed the resulting impression will be in reverse color and position; that is, the ink is actually adhering to what would be furrows of the pattern when viewed from the proper or outer side. If it is deemed inadvisable to try to invert or turn the skin inside out for fear of damaging it, a photograph of the inner ridge detail is made and the negative is printed to give an "as is" position photograph for proper classification and comparison purposes. In order to secure good photographs of the ridge detail it may be advisable to trim the skin, flatten it out between two pieces of glass, and photograph it in that position .

When the entire finger is placed in the solution during the hardening process, the skin, in absorbing the formalin solution, may swell and come loose from the finger. Should this occur, the skin must be removed carefully and the procedure outlined above followed. If, however, the skin still adheres to the finger and is not too wrinkled, ink is applied and prints made. Should the skin be too wrinkled to secure a satisfactory impression, consideration is given to the injection of the tissue builder under the skin as previously mentioned, in order to distend the pattern area. If successful, the finger is inked and printed. This, of course, can be done only when the skin is intact.

Should part of the skin be destroyed to the extent that tissue builder cannot be injected effectively, while examination discloses that the pattern area is present but wrinkled, cut off the entire pattern area from the joint to the tip of the finger . Care must be exercised to insure getting the complete fingerprint pattern as well as cutting deep enough to avoid injury to the skin.

After excision, the flesh is carefully and meticulously removed from the inside by scraping, cutting, and trimming until only the skin remains, or until the specimen is so thin it can be flattened out to remove most of the wrinkles. If the skin is fairly pliable, the operator should attempt to place it over one of his own fingers and try several prints. If the prints secured are not suitable, the piece of skin is flattened out between two pieces of glass and photographed .

The foregoing outline covers the procedures followed in cases involving decomposition in which the outer skin is still present. In many instances of decomposition the outer skin has been destroyed or is in such a condition as to be of no value. It must be emphasized again that the second layer of skin possesses the same ridge detail as the outer layer and this, though finer and less pronounced, is just as effective for identification purposes.

If, from examination, it is apparent that the outer layer of skin is missing and the second layer is intact, the finger should be cleansed, dried, inked, and printed in the usual manner. If the specimen is wrinkled but pliable it may be possible to inject tissue builder, as previously mentioned, to round out the finger, then ink and print it.

Occasionally, some of the outer skin is still attached but is of no value. This skin should be removed by carefully picking or prying it off with a scalpel in such a manner as not to destroy or injure the ridge detail of the second layer. After the outer fragments have been removed, the second layer is cleaned, inked, and printed. In the event the resultant impressions are not suitable for classification and identification purposes, the most likely reason for it is that the ridge detail is too fine to print even though there are few if any wrinkles in it. If this is the case, the finger should be cut off at the second joint and photographed. Should wrinkles which cannot be removed by injecting tissue builder, and which also preclude the taking of suitable photographs, be present, the pattern area is cut off with a scalpel from the first joint to the tip. The flesh is then cut and scraped out as previously described, until the specimen is thin enough to flatten out between two pieces of glass which may be held together by scotch tape. The skin is then photographed.

Occasionally, even after the flattening process it will be noted in the ground glass of the camera that the skin may be seen plainly but the ridge detail is very poor. This difficulty may be due to the poor contrast of the ridges and furrows when using direct lighting. If so, it can be overcome by scraping the skin to transparency and then photographing it by transmitted light . Sometimes, due to the condition of the skin, even though it is tissue thin, it will not be transparent. This can be overcome by soaking the skin in xylene for a few minutes and then photographing it by transmitted light while it is still impregnated with the xylene. If the substance dries too fast to permit proper photographing, the skin should be photographed while immersed in the xylene. Of course, after the skin has been photographed the negative should be printed to give a reverse position so that the print will be comparable with inked impressions on fingerprint cards.

The problem confronting the fingerprint examiner in treating fingers which are desiccated or dried and shriveled is that of distending and softening the skin. Desiccated fingers are generally found to have the outer layer of skin intact and the ridge detail fairly clear. However, due to the shrinking, numerous wrinkles will be present, and as the drying process continues the skin and flesh harden until the fingers become almost as hard as stone.

It is sometimes possible to distend or swell the flesh by utilizing a 1- to 3-percent solution of sodium hydroxide or potassium hydroxide, sometimes referred to as caustic potash. As a matter of caution, this process should be tried with one finger before using it for the remaining fingers. This point of caution is made because of the reaction of the potassium or sodium hydroxide, which is actually one of destruction. While absorption and swelling of the flesh occur, the disintegrating action of the fluid may result in total destruction of the flesh.

The finger to be distended is cut from the hand at the second joint and placed in the hydroxide. When it has resumed its normal size by the absorption of the solution, it is inked and printed. There is no set time for this process. The procedure may require a few hours or as much as several days until suitable results are obtained.

After the finger has been in the solution for about 30 minutes, it should be removed and examined in order to note the extent of the swelling and the reaction of the flesh to the solution. If no material change is noted, the finger is returned to the solution. A close watch is maintained and the finger is examined from time to time.

The solution may cause thin layers of skin to peel from the finger. Should this occur, the loose skin is carefully scraped off and the finger rinsed in water for a few minutes. It is then returned to the hydroxide for continuation of the process.

If, during the course of an inspection, it is seen that the flesh is becoming too soft, the finger should be placed in a 1- to 3-percent solution of formaldehyde or alcohol for several minutes in order to harden it.

If, after several hours in the hydroxide, the finger has not reached its normal size, it should be placed in water for an hour or two. This has a tendency to hasten the swelling. When the finger is removed, it will be noted that a film has coated the surface. This coating is carefully scraped off and the finger is replaced in the hydroxide solution for an hour or so, again scraped if coated, soaked in clean water, etc. This process of alternating from solution to water, scraping, and replacing in hydroxide is continued until desirable results are obtained. The finger is then inked and printed.

The above process will so saturate the finger with solution that it may be too wet to print properly. Accordingly, the finger may be dipped into acetone for several seconds, removed, and be permitted to dry, after which it is inked and printed.

The complete process may take from several hours to as much as 10 days to secure suitable results. If the final results of the above procedure are satisfactory with the one finger being tested, the remaining fingers are given the same treatment. Care must be taken to identify each finger properly as to right index, right middle, etc., to avoid any mixup.

In the event that the reaction of the solution on the first finger treated is not satisfactory and the operator feels that it would be futile to continue the process, the finger should be removed from the solution immediately, washed carefully in water, and placed in formaldehyde to harden sufficiently for it to be handled without causing injury to the ridges. The pattern area is cut off in such a manner that sufficient surrounding surface permits the skin to be trimmed. Then from the cut side the skin is carefully scraped and cut to remove the excess flesh. While the cutting and scraping are being done, from time to time the skin should be soaked in xylene and massaged for purposes of softening to remove wrinkles. When the skin is thin enough and sufficiently pliable, the operator places the skin on his own finger, inks and prints it in the usual manner.

If the results are satisfactory, the same procedure is followed with the remaining fingers. In the event the resultant inked prints are not suitable, the skin should be scraped until it is sufficiently thin to be flattened between two pieces of glass and photographed.

Here again it is pointed out that should there be a poor contrast between the ridges and furrows when using direct lighting, the skin is scraped as thin as possible without tearing and it is then photographed by transmitted light.

There are also included, as cases of desiccation, bodies which have been burned or subjected to severe heat. Often there are cases where the skin has become loose but is hard and crisp, or where the finger has been severely burned and is reduced almost to carbon, yet is firm. In these instances the ridge detail usually has not been destroyed.

When a body which has been severely burned is located, the problems of identification should be anticipated. Accordingly, before the body is removed, a careful examination of the fingers should be made in order to determine if the removal would, in any way, cause damage to the fingers. Should it be felt that because of the condition of the body removal would cause injury to the ridge detail, securing of fingerprints at the scene, or possibly the cutting off of the hands or fingers to avoid destruction of the skin, should be considered. An examination of the fingers may disclose that the outer skin is hardened and is partially loosened from the flesh. It is sometimes possible, by twisting back and forth, to remove this outer skin intact. If this is done, the operator may place the skin on his own finger, ink and print in the usual way.

If the skin is intact on the finger and is not wrinkled, of course there is no problem and the usual method is employed to secure impressions.

Should wrinkles be present and the skin pliable, tissue builder is injected into the bulbs, which are then inked and printed.

In the event the wrinkles cannot be removed in this fashion, the pattern area is cut off and the excess flesh scraped out as before. While the scraping and cutting are being accomplished, the skin should be soaked and massaged in xylene to soften. The skin is then placed on the operator's finger, inked and printed. Should prints made in this manner be unsatisfactory, the next recourse is photography.

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