The Science of Fingerprints Part 23

[Ill.u.s.tration: 396]

After excision, the flesh is carefully and meticulously removed from the inside by sc.r.a.ping, cutting, and tr.i.m.m.i.n.g 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 (exert care to avoid breaking or splitting) is flattened out between two pieces of gla.s.s and photographed (figs. 397, 398, 399).

[Ill.u.s.tration: 397. Inked print made from the finger of deceased before treatment.]

[Ill.u.s.tration: 398. Inked print made after skin was removed and treated.]

[Ill.u.s.tration: 399. Photograph of ridge detail of skin flattened between two pieces of gla.s.s.]

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 p.r.o.nounced, 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 cla.s.sification 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 sc.r.a.ped out as previously described, until the specimen is thin enough to flatten out between two pieces of gla.s.s 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 gla.s.s 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 sc.r.a.ping the skin to transparency and then photographing it by transmitted light (i.e., pa.s.sing light through the skin). 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. (See subtopic of this chapter pertaining to "general photography.") 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.

_Desiccation and charring_

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 pota.s.sium 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 pota.s.sium 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 sc.r.a.ped 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 sc.r.a.ped off and the finger is replaced in the hydroxide solution for an hour or so, again sc.r.a.ped if coated, soaked in clean water, etc. This process of alternating from solution to water, sc.r.a.ping, 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 sc.r.a.ped and cut to remove the excess flesh. While the cutting and sc.r.a.ping are being done, from time to time the skin should be soaked in xylene and ma.s.saged 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 sc.r.a.ped until it is sufficiently thin to be flattened between two pieces of gla.s.s 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 sc.r.a.ped 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 antic.i.p.ated. 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 sc.r.a.ped out as before.

While the sc.r.a.ping and cutting are being accomplished, the skin should be soaked and ma.s.saged 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.

In some instances the fingers of burned bodies will be charred. Such cases require very careful handling as there is a probability of destroying or disturbing the ridge detail through mistreatment. In these instances the procedure is determined by the degree of charring.

In extreme cases the only method of recording is by photographing, using side lighting to secure the proper contrast of ridges and depressions. Obviously, no attempt should be made to ink and roll as the pressure necessary to secure the prints would cause the skin to crumble.

In instances where the charring has not reached the extreme stage the procedures previously set forth should be applied; that is, treatment of the skin by cleaning, softening, inking and printing, or, finally, by photographing (fig. 400).

[Ill.u.s.tration: 400. Photograph of charts used in actual case to establish the ident.i.ty of a charred body, victim of murder. Chart A shows skin removed from one of the fingers treated and photographed.

Chart B shows an inked impression of the same finger during victim's life.]

_Water-soaked fingers_

The third and final type of case which may confront the identification officer concerns the problem of maceration, that is, long immersion of the fingers in water.

One of the cardinal rules for securing legible impressions is that the fingers must be dry. Accordingly, in these cases it becomes a matter of drying the fingers in addition to contending with other difficulties. Usually the skin on the fingers absorbs water, swells and loosens from the flesh within a few hours after immersion.

If an examination discloses the skin to be water-soaked, wrinkled and pliable, but intact, the first step is to cleanse the skin carefully as previously described. Next, wipe the fingertip with alcohol, benzine or acetone, waiting a few seconds for it to dry. The skin is pulled or drawn tight across the pattern area so that a large wrinkle is formed on the back of the finger, then the bulb is inked and printed.

If the skin is broken and hanging loose, but its pattern area is intact, it should be removed from the finger, cleansed and placed in alcohol or benzine (not acetone) for about a minute, then stretched carefully over the operator's finger so as to remove any wrinkles. It may then be printed.

Sometimes the skin is intact on the finger but so wrinkled and hard that it is not possible to draw it tight for inking. In this case it may be advisable to inject tissue builder to round out the bulbs for inking and printing. Should this fail, the ridge detail is photographed on the finger; or the skin is cut off, flattened between two pieces of gla.s.s and then photographed. Here, again, it must be pointed out that when the ridge detail does not show on the surface of the outer skin the underside should be examined, for many times the detail can be seen clearly. Should this be true, of course, the underside is photographed.

In cases where it is noted that the outer skin is gone and the finger is not saturated with water, it is possible to dry the surface sufficiently for inking and printing purposes by rolling the finger on a blotter. If this fails, the finger is wiped off with a piece of cloth which has been saturated with alcohol, benzine or acetone, after which it may be inked and printed.

_Drying the fingers_

In many instances it will be found that the outer skin is gone and the fingers themselves are saturated with water. A quick method of drying out the fingers is to place them in full strength acetone for approximately 30 minutes. The fingers are then placed in xylene for about an hour or until the xylene has overcome the reaction of the acetone. After removal from the xylene the fingers should be placed on a blotter until the surface of the fingers appears dry. They are then ready to be inked and printed.

It will be noted in this procedure that when the fingers are removed from the acetone they dry and harden in a matter of seconds. The purpose of the xylene is to resoften the fingers. After this treatment, should the resulting inked impressions be unsuitable for cla.s.sification purposes, the ridge detail should be photographed.

_X-ray photography_

The use of X-ray photographs (radiography) has been advocated by some for purposes of recording the ridge details in decomposed, desiccated, or macerated cases. Briefly, the procedure involves the covering of the fingers with heavy salts such as bis.m.u.th or lead carbonate, in a thin, even film over the pattern area and then, by the use of the X-ray, reproducing the ridge detail. This procedure necessitates the use of X-ray equipment and a technician skilled in making radiographs.

It is, therefore, an expensive operation. The results of the radiograph in no way compensate for the expense, time, and skill required inasmuch as in those cases where many wrinkles and creases appear in the fingers, especially desiccated specimens, the results have been very poor. In instances where there are no wrinkles or only a few, and where the creases are not too deep, the ridge detail is reproduced very well in the radiograph. In these cases, however, it is usually possible to secure impressions by inking and rolling in the regular way or, should this fail, ordinary photography will certainly give satisfactory results. For economical and practical purposes the use of the X-ray is not recommended.

_General photography_

In the foregoing instances in which it has been impossible to obtain suitable inked impressions it will be noted that the last resort has always been photography. In all probability in advanced cases of decomposition, desiccation, and maceration it may not be possible to secure inked impressions which can be properly cla.s.sified. Hence, it will be necessary to photograph the ridge detail. Accordingly, there are outlined below several methods of photographing the ridges which have been used with success.

In photographing the ridge detail on fingers it has been determined to be most practicable to photograph the finger natural, or 1/1, size inasmuch as comparisons will usually be made with inked impressions which are natural size. Any camera built or adjusted to taking 1/1 size pictures, and with which the lighting may be arranged to best advantage, may be used.