United States. Federal Bureau of Investigation

“ 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. ”

“ A practice which has been of the utmost benefit in the Federal Bureau of Investigation is as follows: When a fingerprint card is taken out of its regular file for any reason, a substitute card is put in its place, to remain until the return of the card. This substitute card, or "charge-out" card, is of a different color from the fingerprint card and slightly longer. On it are recorded the name, the classification formula, and peculiar characteristics, such as scars and peculiar pattern formations, appearing on the original card. ”

“ As previously stated, the fingerprint camera can be readily adapted to the use of photographing fingers or skin specimens for ridge detail. Sometimes it is possible to photograph the skin or finger in the same manner as one does a latent print. There will be instances, however, in which the standard use of the fingerprint camera will not be possible or effective, such as for side light, reflected light, and sometimes transmitted light, or instances in which it is not possible to get the finger or skin flush with the opening of the camera. ”

“ An indication on the fingerprint card to the effect "fresh cut, bandaged" is not sufficient to file the fingerprint card. It is obvious that a fingerprint card bearing these notations cannot be properly classified and filed. The same situation would occur if there were a blister on an individual's finger. The blister temporarily disfigures the ridge detail. When an injury is temporary, the prints, if at all possible, should not be taken until after the injury has healed.
Occupational problems (bricklayers, carpenters, etc.) are definitely a challenge to the identification officer. ”

“ 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.
There is a wide choice of film which can be used for this purpose. The so-called soft films are all good for photographing ridge detail on fingers. Process film is not recommended inasmuch as the film presents too much of a contrast. ”

“ The identification officer will understand the problems of accurately classifying and filing fingerprint cards. He knows there is little value in placing a fingerprint card in the FBI's files with only an approximate or an inaccurate classification.
Every fingerprint card filed in the FBI's file is of value to the particular law enforcement agency which forwarded it, as well as to all other law enforcement agencies which rely on its being correctly classified and filed. ”

“ Care should be exercised so the bulb of each finger is inked evenly from the tip to below the first joint. By pressing the finger lightly on the card and rolling in exactly the same manner, a clear rolled impression of the finger surface may be obtained. It is better to ink and print each finger separately beginning with the right thumb and then, in order, the index, middle, ring, and little fingers. (Stamp pad ink, printing ink, ordinary writing ink, or other colored inks are not suitable for use in fingerprint work as they are too light or thin and do not dry quickly.) ”

“ When it is known to a law enforcement agency that a subject under arrest is an employee of the U.S. Government or a member of the Armed Forces, a notation should be placed in the space for "occupation" on the front of the fingerprint card. Data such as location of agency or military post of assignment may be added beside the space reserved for the photograph on the reverse side of the card.
Many instances have been observed where an individual is fingerprinted by more than one law enforcement agency for the same arrest. ”

“ When the use of the word "delta" in physical geography is fully grasped, its fitness as applied in fingerprint work will become evident. Rivers wear away their banks and carry them along in their waters in the form of a fine sediment. As the rivers unite with seas or lakes, the onward sweep of the water is lessened, and the sediment, becoming comparatively still, sinks to the bottom where there is formed a shoal which gradually grows, as more and more is precipitated, until at length a portion of the shoal becomes higher than the ordinary level of the stream. ”

“ In lieu of a recurve in front of the delta in the inner pattern area, an obstruction at right angles to the line of flow will suffice.
It is necessary that the inner line of flow be fixed artificially. The inner line of flow is determined by drawing an imaginary line between the inner delta and the center of the innermost recurve or looping ridge.
In the central pocket loop, one or more of the simple recurves of the plain loop type usually recurve a second time to form a pocket within the loop. The second recurve, however, need not be a continuation of—or even connected with—the first. ”

“ Inked fingerprints taken for comparison with latent impressions should be as legible and as complete as possible, including the areas not essential to classification, since identifications are often made with these areas. Inked palm prints taken should likewise be complete and clear and should include impressions of the finger joints. Persons not experienced in latent print comparisons should not attempt to evaluate latent fragments, since the area necessary for an identification may be extremely small compared to that of an average inked fingerprint. ”

“ 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. ”

“ 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. ”

“ No matter how definite fingerprint rules and pattern definitions are made, there will always be patterns concerning which there is doubt as to the classification they should be given. The primary reason for this is the fact that probably no two fingerprints will ever appear which are exactly alike. Other reasons are differences in the degree of judgment and interpretation of the individual classifying fingerprints, the difference in the amount of pressure used by the person taking the prints, and the amount or kind of ink used. ”

“ Tented arches and some forms of the loop are often confused. It should be remembered by the reader that the mere converging of two ridges does not form a recurve, without which there can be no loop. On the other hand, there are many patterns which at first sight resemble tented arches but which on close inspection are found to be loops, as where one looping ridge will be found in an almost vertical position within the pattern area, entirely free from and passing in front of the delta. ”

“ 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 (fig. 393) . The thumb, if it is cramped or bent, can generally be straightened by making a deep cut between the thumb and the index finger. ”

“ Skin placed in a formaldehyde solution usually turns a grayish white and becomes firm. However, it will [Pg 141] 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. ”

“ If the opposite finger were a whorl this would be classified as a whorl, and with the same tracing. If a radial loop were opposite, this would be classified as an ulnar loop (if in the right hand) . The ridge count can be obtained with a fair degree of accuracy. If an arch or tented arch were opposite, this impression would be classified as a loop because it looks as if it had been a loop.
[Fig. 356]
In figure 357, the ridge count cannot be determined accurately but it would be classified as a loop, no matter what the opposite finger might be. ”

“ 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. ”

“ Many times it is undoubtedly difficult for the layman to perceive, from a vocal explanation alone, the full import of an expert's testimony, due to its technical nature; consequently, some graphic representation of the facts presented is amply justified and rewarded. The preparation of the charts is ultimately the sole responsibility of the expert using them. As a matter of interest to law enforcement personnel engaged in fingerprint work, a brief explanation of the preparation of such charts follows, along with suggestions and remarks based on long experience in these matters. ”

“ 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. ”

“ Excessive perspiration can be controlled to some extent by the identification officer. Excessive perspiration causes the inked impressions to be indistinct. It is suggested in these cases to wipe the finger with a cloth and then immediately ink the finger and roll it on the fingerprint card. This process should be followed with each finger. It is also suggested that possibly the fingers could be wiped with alcohol, benzine, or similar fluid which would act as a drying agent. ”

“ When an identification bureau receives prints of individuals on whom it already has prints, it is not practical to keep more than one set of prints per person in what may be called the active fingerprint file. ”

“ 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 [Pg 148] across the pattern area so that a large wrinkle is formed on the back of the finger, then the bulb is inked and printed. ”

“ To establish identity, it is necessary to locate several points of identity among the characteristics of the prints. The number of identical characteristics is left to the discretion of the individual but he should be absolutely certain that the prints are identical before treating them as such. Characteristics need not appear within the pattern area, since any ridge formation is acceptable. Quite often excellent ridge detail appears in the second joint of the finger. ”

“ Fingerprint comparisons in this unidentified file can be made on the basis of fingerprints taken from day to day of individuals fingerprinted for criminal identification purposes. A routine may be set up whereby the fingerprints of individuals arrested each day will be compared the following day with the latent fingerprints filed in the unidentified latent file. It is most important that this procedure be rigidly followed from day to day. It is to be borne in mind that the comparisons are made whether the particular person is or is not a suspect in a certain case. ”