The best approach for arriving at the proper exposure time is merely to make a test exposure, develop the film, and from an examination determine if it is underexposed or overexposed. Time the next exposure accordingly, until satisfactory results are obtained.
As has been mentioned previously, when photographing the ridges on fingers or skin, the ridge detail will be in reverse position, the opposite from an inked impression made from the same skin or finger. (This is true except in those cases in which the underside of the epidermis is photographed.) Accordingly, when the negative is printed, it should be printed gloss side to sensitive side of paper to give the position comparable to an inked print made from the same skin or finger. In order to avoid error or confusion a notation should be made on the photograph of each finger, or, if they are cut and mounted on a fingerprint card, point out that the position has been reversed and that the prints are in their correct position for classifying and searching. Otherwise, it is possible that the right hand may be mistaken for the left hand and vice versa.
If the underside of the epidermis or outer skin is being photographed, the negative should be printed in the normal manner, that is, emulsion side of negative to sensitized side of paper. Here, reversal of position is not necessary for when the ridge detail is viewed from the underside it appears to be in the same position as the inked impression normally is reflected on a fingerprint card.
Care should be taken to see that each photograph is labeled correctly to indicate the finger it represents, such as right thumb, right index, right ring, etc. It is imperative that no error occurs in such labeling, inasmuch as it is highly probable that the resultant classification would be incorrect and failure to make an identification might very easily follow.
The foregoing has dealt with the securing of fingerprints of unknown deceased persons for identification purposes. The basis for such action is the presumptive possibility that the unknowns had been fingerprinted previously and through this medium might be identified.
Another type of problem, however, arises with the finding of a deceased infant. It can be safely assumed that the possibility of there being in existence a set of known fingerprints of the infant is extremely remote. Nevertheless, in view of the fact that many hospitals throughout the country, as part of the general routine of recording a birth, secure the infant's footprints, it would follow that there could be a remote possibility of identifying the deceased infant through its footprints. The foregoing principles and procedures would then apply in securing the foot impression of a deceased infant. It is fully realized that in practically all cases involving the finding of an abandoned infant corpse the infant is probably illegitimate issue and delivery did not occur in a hospital, but there have been instances where such was not the case.
The importance of securing footprints of deceased infants killed in a common disaster cannot be overemphasized. Such disasters may involve the death of infants of lawful issue, and in many instances there are hospital footprint records available which may prove of value as a positive means of identification.
The methods described are intended to record, either by printing with ink or by photographing as legibly as possible, the ridge details of the tips of the fingers of unknown dead for identification purposes. The securing of the impressions enables the fingerprint examiner to classify and search them through a file. This "search," of course, means merely to make a comparison of the deceased's prints with the prints of known individuals.
It is well to bear in mind the fact that the dermis or epidermis may have undergone certain physical changes and that in order for the fingerprint examiner to make a proper comparison he must know the changes which can and do occur. Otherwise, he may fail to make an identification (fig. 403).
Fig. 403
[Fig. 403]
Consider first the epidermis or outer layer of skin in cases of maceration (the skin is water soaked). There may be considerable swelling. The ridges become broader and are more distinct. An inked impression in such an instance may show a pattern larger in area than a print made from the same finger when the person was alive. Also, if the skin is on the finger but is loose, inking and rolling could distort the impression so that some of the ridge formations would seem to be in a different alignment from corresponding details in a print made during life. When decomposition commences, what are really solid ridges may be broken, giving rise to the possibility that there appear to be more characteristics than there actually are (figs. 404 and 405).
Fig. 404-405
[Figs. 404-405]
The existence of wrinkles may also cause the impression to acquire an appearance of dissimilarity when compared with the original inked print.
With respect to cases of desiccation, there will probably be shrinkage, hence, the impressions made may appear smaller than in life and the ridges will be finer. In cases in which the epidermis has been lost and there remains only the dermis or second layer, there will usually be shrinkage with the same results. Here also, wrinkles, if present, may cause a difference in appearance from the normal print.
In addition to shrinkage and wrinkles in cases involving the second layer of skin, there is a radical change in the appearance of the ridges themselves. The second or dermal layer of skin is composed of what are called dermal papillae which have the appearance of minute blunt pegs or nipples. The dermal papillae are arranged in double rows (fig. 406). Each double row lies deep in a ridge of the surface or epidermal layer and presents the same variations of ridge characteristics as are on the outer layer of skin except that they are double. Accordingly, when the second layer of skin is printed or photographed, the ridge detail will appear in double. That is, the ridges will appear as though they were split. This may well confuse the fingerprint examiner in that what may be a loop having 10 ridge counts may appear to be a loop having 20 ridge countswhen the impression is made from the second or dermal layer of skin. These double rows of ridges are finer and not as sharp as the detail on the outer skin, which adds to the difficulty of arriving at a correct classification and making a proper comparison.
Fig. 406
[Fig. 406]
The above techniques and procedures have been dealt with upon the basis that the law enforcement officers would, when a corpse has been found, attempt to secure a set of finger impressions in an effort to identify the unknown dead. If, however, the officer feels that the job is too difficult or is beyond his scope, consideration should be given to cutting off the hands or fingers of the deceased and forwarding them to the Identification Division of the FBI for processing. If this course is decided upon, it is reiterated that local statutes governing the cutting of the dead must be complied with and proper authorization must be secured.
In order to facilitate the transmission of such specimens to the FBI the following suggestions are made:
First, it is deemed most desirable, when possible, to have both of the hands, severed at the wrist, forwarded in their entirety (fig. 407). It isdesired that the hands, rather than each separate finger, be sent inasmuch as it eliminates the possibility of getting the fingers mixed up or incorrectly labeled. If, however, it is not possible to send the hands for some reason, then, of course, the fingers should be cut off and forwarded. In cutting, the fingers should be cut off at the palm beginning with the right thumb, then the right index, ring, etc., just as though they were to be printed. As soon as each finger is cut off it should be placed in an individual container, such as a small glass jar, and immediately marked as to which particular finger it is.
Fig. 407
[Fig. 407]
In the event that the hands or fingers of more than one dead are being transmitted, it is absolutely necessary that not only the fingers be properly labeled but that each body also be given an identifying number or symbol which must be indicated on the hands or fingers cut from that body as well, in order to avoid the embarrassing situation of identifying the hands and not knowing from which body they were cut.
In shipping, the hands, fingers, or skins may be placed in preserving solutions such as 5-percent solution of formaldehyde, 5-percent solution of alcohol, or embalming fluid. When hands or fingers are desiccated (dried out), however, it is most desirable that they be placed in airtight containers and sent without any preservative. If glass containers are used, the specimens should be packed in such a manner as to avoid breakage. Dry ice is a suitable preservative for transmitting such specimens but it should not be used when shipping will take more than 24 hours.
In making up a package using dry ice, the hands or fingers, properly tagged, should be placed in cellophane or paper bags. A material such as sawdust, shavings or similar packing which acts as an insulation is placed around the specimens. A sufficient amount of dry ice is then placed in the package which is then packed tight with more sawdust or shavings. The dry ice should not be in direct contact with the cellophane or paper bags which contain the hands or fingers.
A letter covering transmittal of the specimens should be prepared in duplicate. It should, of course, indicate the sender. The names of any probable victims, sex, race and approximate age of the deceased should, if such information is available, be secured from the coroner or medical examiner and be included in the letter. A copy of the letter should be placed in the package. The original should be mailed separately. Both letter and package should be addressed as follows:
DirectorFederal Bureau of InvestigationU.S. Department of JusticeWashington 25, D.C.Attention: Identification Division—Latent Fingerprint Section.
DirectorFederal Bureau of InvestigationU.S. Department of JusticeWashington 25, D.C.
Attention: Identification Division—Latent Fingerprint Section.
If the package contains glass jars it should be marked "Fragile" to insure careful handling in transit.
The package should be sent railway express, prepaid, or, where there is need for speed, by air express, prepaid. When they are received by the Identification Division, the specimens will undergo various treatments which may necessitate further cutting, scraping, etc. In all cases, regardless of condition, the specimens will be returned after examination.
All of the foregoing matter has dealt with instances in which it has been assumed that all ten fingers are available, or a sufficient number of the fingers of a deceased have been secured and impressions suitable for searching through the fingerprint files of the FBI have been recorded.
There will be cases, however, where only a few, or possibly only one, of the fingers has sufficient ridge detail for identification. In such instances a search through the FBI files would be impractical. This, however, does not preclude the possibility of making a positive identification by the use of the one finger. Though a search through the file is not possible, a comparison can be made with the fingerprints of individuals who it is thought the deceased may be or, in some instances, with the fingerprints of missing persons.
In this connection, where one or only a few fingers are forwarded to the FBI, the names of all possible victims should also be submitted. The fingerprints of those individuals, if available, will then be taken out of file and compared with the ridge detail on the finger of the deceased in an endeavor to establish a positive identification. Many such identifications have been effected.
In conjunction with the usual services afforded authorized law enforcement agencies, the services of an FBI fingerprint expert are also made available in those cases where expert testimony is necessary to establish the identity of the deceased through fingerprints, providing, of course, such an identification has been made.
Extreme caution should be exercised in the case of the chemicals previously mentioned in this article. Acetone, alcohol, benzine, and xylene are highly inflammable and should neither be used near open flames nor while the operator is smoking. The fumes given off by acetone, benzine, xylene, and formaldehyde are toxic and may cause sickness. They should be used in a well-ventilated room only. It is also suggested that the fingerprint examiner wear rubber gloves when using acetone, benzine, xylene, formaldehyde, potassium hydroxide, or sodium hydroxide. These chemicals will cause the skin to peel. Strong concentrations may cause burns.
In conclusion, it is pointed out that the procedures and techniques which have been described are those currently being used by the fingerprint experts of the FBI. These methods are fast and the results have been most satisfactory. This Bureau does not claim, however, that satisfactory results cannot be achieved through variations thereof or different methods.
For the information and assistance of officials who desire to establish a local fingerprint identification bureau, the following suggestions are being made to indicate the principal materials necessary to equip such a bureau:
For the purpose of taking fingerprints there should be a stand with a clamp for holding the fingerprint cards steady. This latter item is necessary to prevent smudging the prints. A tube of printer's ink is used. The ink is applied by a roller to a glass plate upon which the fingers are inked before being rolled on the cards. The complete equipment for the above process may be secured from a number of commercial sources or it can be made. Figure 408 depicts an inking stand.
Fig. 408
[Fig. 408]
It is suggested that the fingerprint card be white, light cardboard, 8 by 8 inches, slightly glazed. This size is convenient, as it allows all the space necessary for recording the classification of the prints and general descriptive information concerning the individual. In the event the new bureau desires to contribute copies of its fingerprints to the Federal Bureau of Investigation, the latter will, upon request, gladly furnish fingerprint cards for the purpose together with envelopes and instructions on how to take fingerprints. It is suggested that the new bureau design its cards similar to those furnished by the Federal Bureau of Investigation, as these have been designed after special study and have been found to be satisfactory over a long period of time. Figures 409 and 410 show the fingerprint side and reverse side of the criminal fingerprint card used by the Federal Bureau of Investigation.
Fig. 409
[Fig. 409]
[Enlarge]
Fig. 410
[Fig. 410]
[Enlarge]
In classifying and comparing fingerprints it is necessary to use a magnifying or fingerprint glass. Such instruments can be obtained from various commercial sources. Figure 411 shows the type of magnifying glass used by the Federal Bureau of Investigation.
Fig. 411
[Fig. 411]
The fingerprint cards should be filed according to fingerprint classification sequence in cabinets, preferably steel. It is further suggested that the cabinets be three drawers high, with each drawer divided into three rows for filing. Such cabinets or similar ones can be obtained from various commercial sources. Figure 412 shows the type of fingerprint cabinet used in the Federal Bureau of Investigation.
Fig. 412
[Fig. 412]
In order to facilitate the location of classification groups, it is suggested that guide cards be placed in the rows of fingerprint cards atfrequent intervals. These guide cards should be slightly longer and heavier than the fingerprint cards and should have small tabs on the top to hold classification identifying symbols. Figure 413 shows the type of guide card used by the Federal Bureau of Investigation.
Fig. 413
[Fig. 413]
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. By indicating the date and reason for charging out the original card, the Bureau is able to keep an accurate check on the whereabouts of all prints at all times. It is suggested that the local bureaus adopt a practice of this kind whenever a fingerprint card is drawn from the files and it is known that it may be out for a period oftime longer than the remainder of the day on which it is drawn. Figure 414 shows the type of charge-out card used in the FBI.
Fig. 414
[Fig. 414]
[Enlarge]
Each fingerprint card handled by the bureau should receive a fingerprint number and these numbers can be assigned in consecutive order.
As the bureau increases in size, it will be found a source of much convenience to have fingerprints of males and females kept in separate files.
There will be times when it may be necessary to locate an individual's fingerprints when no current fingerprints are available, but the name with a police number or the classification is known. In order to facilitate work of this nature, as well as to keep a complete record and check on each set of fingerprints, it is necessary that the files be indexed in a manner similar to that in which books in a library are indexed.
In this connection, for each fingerprint card there is prepared an index card. On this the name of the individual is placed, with all known aliases,the fingerprint classification formula, the police or arrest number, the date of arrest or other action. It is desirable, also, to have on this card such general information as age, height, weight and race. Figure 415 shows the front of a suggested type of 3- by 5-inch index card.
Fig. 415
[Fig. 415]
[Enlarge]
Figure 416 shows the reverse side of the 3- by 5-inch index card. These are filed alphabetically in special cabinets. An index card also should be made for every alias which an individual has used. Figure 417 shows an electrically operated file cabinet in which the index cards are filed. It is suggested that the alias cards be of a different color from the one bearing the correct name, known as the "Master." Each alias card also should have typed on it the correct name of the individual, for purposes of reference and cross-checking. For convenience and accuracy these files, as in the fingerprint files, should also have suitable guide cards.
Fig. 416
[Fig. 416]
Fig. 417
[Fig. 417]
It is advisable to make use of charge-out cards when original index cards are drawn from the files. Figure 418 shows a charge-out card.
Fig. 418
[Fig. 418]
[Enlarge]
To supplant the 3- by 5-inch index cards mentioned above, many law enforcement agencies have found it desirable to use a separate sheet,sometimes referred to as a "History Sheet" or "Information Sheet," containing the complete case history of the subject involved. These separate sheets can be filed by fingerprint number sequence and contain not only the data such as the known aliases, the fingerprint classification formula, the arrest number, and other essential items which are set out on the 3- by 5-inch cards as heretofore described, but also contain a concise summary of the subject's arrest history, particularly with reference to his criminal activities in the particular city. They may also contain a summarized case history with respect to each arrest or commitment, including such items as the date and place of arrest, complete home address, relatives, the essential facts concerning the prosecution of charges, and the ultimate disposition.
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. In theseinstances the better print should be designated a "Master" print by having the word "Master" stamped thereon. It should be given a number, to be known as the master number, which number should also be placed on all other sets of prints which may be found to be identical with the "Master" print. The "Master" print is placed in the active files. The extra prints are placed together in a heavy folder with their master number stamped thereon. This jacket folder is then filed in a separate cabinet. Also, if copies of all information regarding an individual, photographs, and FBI transcript of record are kept in this folder, his complete record will always be assembled in an easily accessible unit. The "Master" number should also be placed on the index card and all the alias cards of the individual. Also, each new alias and arrest number should be placed on the original index card. The additional records are kept in folders which are arranged in numerical order, beginning with Nos. 1, 2, 3, and so on.
A further suggestion in connection with the maintenance of this folder file, besides the use of a separate "Master" numbering system, is the use of the arrest fingerprint number. As indicated previously, each person arrested and fingerprinted is assigned a number. This number appears on the fingerprint card, name-index card, and photograph. The practice of handling every new arrest fingerprint card in the bureau should include searching the fingerprint card in the fingerprint file to ascertain if the subject has a previous record. If the subject does not have a previous record, a new number should be assigned. In this connection it is noted that only one copy of the fingerprint card should be maintained in the file by fingerprint classification. To indicate the new arrest on the oldindex card, the date of the new arrest can be shown. Whether the bureau follows the "Master" numbering system or the "previous arrest" numbering system should make very little difference in the ultimate purpose. All extra copies of fingerprint cards, complete record sheets, photographs, and all information pertaining to the individual are filed away in the folder file. This complete record is readily accessible at all times. It will now be found that the bureau has a complete record of each individual who has an arrest record on file, with provision made for accurate cross-referencing and checking between names and fingerprints.
It is important to the bureau to have complete information concerning the ultimate disposition on each arrest fingerprint card. If the disposition of a charge is known at the time the person is fingerprinted, this fact should be indicated in the space provided on the fingerprint card. For example, in the case of an individual who is arrested, fingerprinted, and turned over to the county jail, this disposition can be indicated on the fingerprint card which is forwarded to the Federal Bureau of Investigation. The fingerprint card should not be held by the bureau pending final disposition of the charge.
In those cases where the disposition is pending prosecutive or court action, a separate 3- by 5-inch disposition file can be maintained. On these cards information concerning the name, fingerprint number, race, sex, charge, name of the arresting officers, and the fingerprint classification should appear. These cards are filed in a pending-disposition file. The 3- by 5-inch disposition cards are made at the time the fingerprints of the person are taken. When the final disposition is obtained it should be noted on the card. In those cases where there is only one fingerprint card in the bureau, the disposition can be noted on the name-index card or the reverse side of the bureau's fingerprint card. In those cases where there is a jacket-folder file for the individual this disposition card can then be placed in the folder.
"Disposition Sheets" (No. R-84) can be obtained from the Federal Bureau of Investigation for forwarding this information so that the files of the FBI will have complete information concerning the arrests. At the time the final disposition is obtained, these disposition sheets can be completed and forwarded to the Federal Bureau of Investigation.
When persons whose fingerprints are on file are reported as deceased, the prints should be taken from the active file and assembled with anyother prints of the person concerned. These should be plainly marked "Dead" and filed in a separate cabinet or section. All the index cards on this individual should also be marked "Dead" and filed in a separate section. These should be retained for possible future reference.
In this connection, "Death Notice" forms (No. R-88) can be obtained from the Federal Bureau of Investigation so that information concerning these deaths can be properly noted in its fingerprint file.
It is not necessary for a bureau to send a regular fingerprint card to the Identification Division of the Federal Bureau of Investigation on individuals who have been arrested repeatedly and whose previous records are known to the local law enforcement agency. In such cases the "Record of Additional Arrest" form should be used.
Complete information must be given on this form. It is imperative that the FBI number and the finger impressions be placed on this form. The Identification Division of the Federal Bureau of Investigation will send no answer upon receipt of this form.
The form will be placed in the FBI number folder on the individual and later when a regular fingerprint card is received the arrest information from all the forms will be compiled and included on the subject's record as "supported by fingerprints."
"Record of Additional Arrest" forms (No. 1-1) can be obtained from the Federal Bureau of Investigation.
All wanted notices containing fingerprints, including the wanted notices inserted in the FBI Law Enforcement Bulletin, should be filed in the fingerprint file by classification formula, and the names appearing on these wanted notices should be indexed and placed in the name files. Concerning the small wanted notices inserted in the FBI Law Enforcement Bulletin, a suggested procedure would be to paste each individual notice on a blank 8- by 8-inch white card. The wanted notices are filed by the fingerprint classification and the names indexed and placed in the name file. When an apprehension notice is received concerning the wanted notice, a proper notation should be made on the name card and the wanted notice in the fingerprint file. If these canceled wanted notices endanger the efficiency of the file, it is suggested that the name-index card and the fingerprint-wanted notice be destroyed. Should the bureauadopt this practice it is suggested that the 8- by 8-inch cards be used again for other wanted notices. In this manner it would be possible to use the blank card for eight of these notices.
The Federal Bureau of Investigation will make available to law enforcement agencies a special "Wanted Notice" form (No. 1-12) in order that they can place wanted notices against the fingerprints in the files of the FBI.
Arrangements should be made to procure a camera for taking photographs of the persons fingerprinted. This is known as a "mugging" camera and various types are on the market. It is believed that the photographs should include a front and side view of the person. In most instances a scale for indicating height can be made a part of the picture even though only the upper portion of the individual photographed is taken. Of course, if the scale is used, the person photographed should be standing even though only the upper portion of the body appears in the photograph. The necessary lights should be provided for obtaining photographs. A standard set of scales should be obtained in order that the correct weight can be ascertained.
The negatives and photographs can be filed by fingerprint number in a separate file. In those cases where the individual has more than one arrest all the photographs can be placed in the jacket-folder number file. The negatives, in these instances, can remain in the photograph file.
To adequately develop the latent prints at crime scenes, it is necessary that the proper equipment be provided. This equipment includes latent fingerprint powders, brushes, lifting tape, fingerprint camera, searchlight, and scissors. All of this equipment can be obtained from commercial fingerprint supply companies. Figure 419 shows some of the equipment used by the FBI. The techniques of developing latent fingerprints and their uses are more fully explained in the following chapters.
Fig. 419
[Fig. 419]
It is believed that by following the basic ideas outlined, the officials of law enforcement agencies can be assured of best results in establishing and maintaining a small identification bureau. For further information, the Federal Bureau of Investigation will furnish to duly constituted law enforcement officials any additional data which may be of material assistance in the maintenance of such a bureau.
Each ridge of the fingers, palms, and soles bears a row of sweat pores which in the average person constantly exude perspiration. Also, the ridges of the fingers and palms are in intermittent contact with other parts of the body, such as the hair and face, and with various objects, which may leave a film of grease or moisture on the ridges. In touching an object, the film of moisture and/or grease may be transferred to the object, thus leaving an outline of the ridges of the fingers or palm thereon. This print is called a latent impression, the word "latent" meaning hidden, that is, the print many times is not readily visible.
Latent impressions, regardless of the area of the ridges present, are of the greatest importance to the criminal investigator as identification of them may solve the crime and result in successful prosecution of the subject. Consequently, every effort should be made to preserve andidentifythem.
Visible prints in mediums such as blood, grease, dirt, or dust are equally important to the investigator but, strictly speaking, are not latent impressions.
A search of the crime scene should be conducted in a logical manner. Points of entry and exit should be examined, along with surfaces or objects disturbed or likely touched during the commission of the crime. The examiner should wear a pair of light cloth gloves and handle an object only insofar as is necessary and then only by edges or surfaces which are not receptive to latent impressions. A record of the exact location of a print on an object and of the object itself should be made, since these facts may be of the utmost importance in any trial resulting from the investigation. No one should handle an object other than the examiner himself.
Portable articles removed should be labeled or marked so that they may be readily identified thereafter.
The beam of a flashlight played over the surface of an object will frequently show the location of latent impressions, although this is not an infallible test for their presence.
Evidence should be examined as soon as feasible after its discovery.
Following the location of any latent prints at the scene of a crime, the prints of all persons whose presence at the place under inspection has been for legitimate purposes must be excluded from further attention. It is advisable, therefore, during the initial stages of an investigation where latent prints are found, to secure the inked prints of all membersof the household, the employees, and any police or other officials who may have touched the objects on which the latent impressions were found. Inked prints taken for this purpose are referred to as elimination prints.
Due to the fragmentary nature of most latent prints it is not possible to derive a classification which makes a file search practicable. A latent impression may be identified, however, by comparison with the prints of a particular suspect.
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.
Articles which are to be transported by mail or express should be so packed that the surfaces bearing latent impressions are not in contact with other surfaces. This may be accomplished by mounting the articles on a piece of fiber board or plywood. The board should then be secured in a box so that the objects will not touch or be shaken against the sides in transit. The package should be plainly marked "Evidence," to prevent inadvertent handling on opening. Cotton or cloth should never be placed in direct contact with any surface bearing latent prints.
Any number of paper or cardboard specimens may be placed in a single protective wrapper, since contact with other surfaces does not harm latents on such objects. Lifts, negatives and photographs are readily enclosed with letters.
An explanatory letter should accompany all evidence. If it is necessary to pack the evidence separately, a copy of the letter should be placed in every package so that the recipient will know immediately the import of the contents. All items of evidence should be marked and described exactly in the accompanying letter so that they will not be confused with packing material of a similar nature, and to provide a check on what the package should contain.
In addition, the letter should include for record purposes a brief outline of the crime, i.e., type, date and place of occurrence, and names of victims and subjects. If suspects are named for comparison, sufficient descriptive data should be set out to permit location of their fingerprint records. This information, in preferential order, comprises the individual's complete name, aliases, FBI number, date of prior arrest or fingerprinting, fingerprint classification, date and place of birth, and physical description.
Evidence is preferably forwarded by registered mail or railway express, as these means provide records of dispatch and receipt.
Elimination or suspect fingerprints are best enclosed with the evidence itself, with a notation as to the type of prints forwarded.
The sole purpose in "developing" a latent impression is to make it visible so that it may be preserved and compared. Various powders and chemicals are used for this purpose. When a latent print is plainly visible, it should be photographed before any effort is made to develop it.
No attempt should be made to brush or apply powder to prints in dust, obviously greasy prints, or bloody prints, as this will almost surely destroy them. Objects which have been wet or immersed in water may still bear identifiable latent impressions. Before any examination is attempted, however, the object must be dried.
Powder brushed lightly over a latent-bearing surface will cling to grease or moisture in the ridges of a latent print, making it visible against the background. Obviously, a powder should be used which will contrast with the color of the surface. Photographic contrasts should also be considered.
A gray powder and a black powder are adequate for latent print work. Many fingerprint powders of various colors and compositions are available from fingerprint supply houses but none are superior to the gray and black.
A very small amount of powder is placed on the brush for application to the surface. Once the contour of a print is visible, the brush strokes should conform to the direction of the ridges. All excess powder should be brushed from between the ridges. Too much powder and too little brushing are the chief faults of beginners.
Gray powder is used on dark-colored surfaces. It is also used on mirrors and metal surfaces which have been polished to a mirrorlike finish, since these surfaces will photograph black with the fingerprint camera.
Black powder should be applied to white or light-colored surfaces.
Aluminum powder affords the same contrast as the gray. Gold and red bronze powders, although of a glittering appearance, will photograph dark and should consequently be used on light-colored surfaces. Dragon's blood powder is a photographically neutral powder and may be dusted on either a light or dark surface.
On clear transparent glass, either gray or black powder may be used, it being necessary only to use a contrasting black or white background when photographing.
Prints should be lifted after photographing. Both rubber and transparent tape are available for this purpose. Rubber lifting tape is procurable in black or white 4" x 9" sheets and has the adhesive surface protected with a celluloid cover. A black powder print should obviously be lifted on white tape and a gray powder print on black tape.
Gold bronze and red bronze powders should be lifted on white tape, aluminum on black. Dragon's blood may be lifted on either black or white.
After cutting a piece of tape sufficiently large to cover the entire latent print, the celluloid covering is removed and the adhesive side applied to the latent. The tape should be pressed evenly and firmly to the surface, taking care not to shift its position. It is then peeled gently from the surface and the piece of celluloid placed over the print to protect it. The operator should handle the lift in such a manner that he will leave no prints of his own on the adhesive surface. A small paper identification tag bearing the initials of the operator, date, and object from which lifted should be placed under one corner of the celluloid, or this information may be written on the back of the lift itself if it can be done in a permanent, legible manner.
If an excessive amount of powder adheres to the latent print, a more legible print may sometimes be obtained by lifting a second time (on a new piece of tape, of course).
It should be noted that a print lifted on rubber tape is in a reverse position. Consequently, in preparing a photograph of a print on such a lift, it will be necessary to print the negative from the reverse side in order for the print to appear in its correct position for comparison. Preparation of such photographs should not be attempted by persons of inadequate knowledge and experience.
Transparent tape with a durable adhesive surface is available in 1" to 2" widths for fingerprint work. The common variety of transparent tape is not suitable due to the deterioration (drying) of the adhesive surface. The print on a piece of transparent tape is in correct position. Transparent lifts should be affixed to a smooth, grainless, opaque background of a black or white color contrasting with the powder used. Every effort should be made to avoid air bubbles under such lifts. In no instance should a transparent lift ever be folded back on itself or stuck to another piece of such tape as a backing, since it is generally not possible to determine the correct position of such a print.
Groups of latent impressions, such as those of adjacent fingers or fingers and palms which appear to have been made simultaneously, should be lifted as units, that is, on a single piece of tape, as this may facilitate the task of making comparisons.
Chemical treatment in the development of latent finger impressions on paper, cardboard, and newly finished or unpainted wood may involve a slightly more complicated technique than that in which powders are utilized, but the results justify the additional effort.
It is very strongly recommended that powders not be applied to articles of the above types. This recommendation is made for several reasons. First, powders cannot be removed from paper and possibly may interfere with some types of document examinations. In this connection, they are likely to prevent restoration of the specimen to a legible condition. Powders will not develop as many latent impressions as chemicals on paper or cardboard. In some cases they will obscure latent impressions subsequently developed chemically.
Neither scientific training nor complete knowledge of the chemical processes involved is necessary for one to become proficient in the use of chemical developers, two of which will be discussed more fully. These two, iodine and silver nitrate, are the most commonly used, inasmuch as they are relatively inexpensive, readily procurable, effective, and easy to apply.
All specimens which are treated should be handled with tweezers or gloves.
When iodine crystals are subjected to a slight amount of heat they vaporize rapidly, producing violet fumes. These fumes are absorbed by fatty or oily matter with which they come in contact. If the specimen treated bears latent impressions which contain oil or fat, the print is developed or made visible by the absorption of the iodine fumes and the ridges of the print appear yellowish-brown against the background.
Iodine prints are not permanent and begin to fade once the fuming is stopped. It is necessary, therefore, for the operator to have a camera ready to photograph the prints immediately.
Control of the fumes is achieved by using the crystals in an iodine gun or fuming cabinet. The iodine gun may be assembled by the individual examiner, by a druggist, or it may be purchased through a fingerprint supply house.
Material for making the iodine gun, as well as iodine crystals, may be procured from a chemical supply house or through a druggist. The gun itself consists essentially of two parts. One tube (the end of the gun through which the breath is blown) contains a drying agent such as calcium chloride, to remove moisture from the breath. Without this, themoisture from the breath and saliva would condense at the end of the gun, drip onto the specimen and cause stains which might prove indelible. The second tube contains a small amount of iodine crystals which are vaporized by the heat of the breath, augmented by the warmth of the hand cupped around the tube containing the iodine. This vapor is blown onto the specimen (fig. 420). Glass wool serves to hold the calcium chloride and iodine in place.
Fig. 420
[Fig. 420]
Due to the amount of physical exertion involved, the gun is generally limited to the examination of a few small specimens. Where a large number of specimens are to be treated, the fuming cabinet, a box-shaped wooden receptacle with a glass front and top permitting the operator to control the amount of fumes in the cabinet and observe the development of the latent impressions, is used (fig. 421). The fumes are generated by placing a small alcohol burner under an evaporating dish containing the iodine crystals. This is set in a hole cut in the bottom of the cabinet. As soon as the fumes begin to appear in sufficient amounts, the burner is removed. The specimens may be hung in the cabinet by wooden clothes pins fastened to a removable stick which is supported by wooden strips affixed near the top edges of the cabinet. The top of the cabinet is removable to permit access. Diagrams for the construction of the iodine gun or fuming cabinet will be furnished on request to members of the law enforcement profession.
Fig. 421
[Fig. 421]
Many specimens bear small, greasy areas which, in addition to any latent impressions of a greasy nature, will also appear yellowish-brownafter exposure to iodine fumes. All these stains will eventually disappear if the specimen is placed in a current of air from a fan or vent. All latent impressions on an object will not be developed by the iodine process but only those containing fat or oil. Due to this fact and the fact that iodine evaporates from the surface, it is used prior to (it cannot be used afterward), and in conjunction with, the silver nitrate process.
No ill effects have been noted from contact with small amounts of iodine vapor but prolonged or excessive contact will produce irritation of the skin and respiratory passages. To prevent gradual loss of the chemical through evaporation and the corrosion of surrounding metal surfaces, iodine crystals should be kept in an airtight container when not being used.
The development of latent impressions with silver nitrate is dependent on the fact that the sodium chloride (the same substance as common table salt) present in the perspiration which forms the ridges in most latent impressions reacts with the silver nitrate solution to form silver chloride. Silver chloride is white but is unstable on exposure to light and breaks down into its components, silver and chlorine. The ridges of the fingerprints developed in this manner appear reddish-brown against the background. Immersion in the silver nitrate solution will wash traces of fatand oil from the paper; consequently, it is necessary to fume the specimen for latents of such a nature prior to treatment with silver nitrate.
Once the requisite equipment is assembled, the steps in the process are these:
Dip the specimen in the solution, blot and dry it, expose to light, and photograph latents when contrast is good.
Chemically standardized solutions are not required for the successful application of this process. It has been determined through long practice that a 3-percent solution of silver nitrate is adequate for the purpose, although concentrations up to 10 percent are sometimes used. A solution of approximately 3 percent may be prepared by dissolving 4 ounces of silver nitrate in 1 gallon of distilled water. Smaller quantities of 3-percent solution are made by using the components in the same proportion. For instance, one quart of water will require 1 ounce of the crystals. For a 10-percent solution, use 13-1/3 ounces of crystals per gallon.
An alcohol solution may be preferred. This is prepared by mixing 4 ounces of silver nitrate crystals, 4 ounces of distilled water, and 1 gallon of grain alcohol, 190 proof. The alcoholic solution dries faster, and when treating paper bearing writing in ink, it is less likely to cause the ink to run. On the other hand, the alcoholic solution is much more expensive and there is some loss by evaporation while in use.
The solutions may be used several times before losing their strength and when not in use should be kept in brown bottles in cupboards to retard deterioration. If the strength of the solution is doubtful, the operator should attempt to develop test latent impressions before proceeding on evidence.
Silver nitrate crystals and distilled water in small amounts are obtainable from druggists or in large amounts from chemical supply houses. Dealers in distilled water are located in many communities.
Tap water should not be used in the preparation of the solution because it generally contains chemicals which will partially neutralize the silver nitrate.
It is suggested that the solution be placed in a glass or enamelware tray approximately 18 by 12 by 5 inches for use, a size used in photographic development. Treatment with this solution is called "silvering." The specimen is immersed in the solution so that the surfaces are completely moistened, then taken out, placed between blotters to remove the excess solution, and dried. The drying is readily accomplished with an electric hair dryer. Blotters may be dried and used several times before discarding. It is not necessary to work in a dark room. Work in an illuminated room but not in direct sunlight. Soaking the specimen in the solution does not aid development and is actually undesirable as it requires a longer drying time. The specimen should be reasonably dry before exposing to the light, otherwise the latent prints may be developedwhile the paper is still wet, thus necessitating drying in subdued light to prevent darkening.
Development of the latent impressions occurs rapidly when the specimen is exposed to a blue or violet light source. A 1,000-watt blue or daylight photographer's lamp, a mercury arc (most ultraviolet lamps are of this type), or carbon arc is excellent for the purpose (fig. 422). If a weaker light is used, a stronger mixture of the solution should be prepared. For instance, if a 300-watt bulb is used, the 10-percent solution would be preferable. Direct sunlight will cause the latent impressions to appear very rapidly and if several specimens are exposed at once it is not possible for a single operator to properly control the development. Sunlight coming through a window pane will serve for development. Where fingerprints containing sodium chloride (normally exuded from the sweat pores in the ridges) have been deposited, the silver chloride formed will darken against the background.
Fig. 422
[Fig. 422]
As soon as the ridge detail of the prints is clearly visible, the paper should be removed from the light. Continued exposure will darken the paper and the contrast will be lost.
Paper so treated should be kept in darkness; that is, in a heavy envelope or drawer until ready to photograph.
Immediate photographing, as in the case of iodine prints, is not always essential, since the prints are permanent and become illegible only through eventual clouding of the background. Prompt photographing is recommended, however, as, in exceptional instances, silver-nitrate prints have become illegible in a matter of hours. Darkening ordinarily will occur slowly if the paper is preserved in absolute darkness, and silver-nitrate prints so preserved more than 10 years have been observed to be quite clear.
Items such as cardboard cartons, newspapers, road maps, large pieces of wrapping paper, or smooth, unpainted wood surfaces, too large for dipping, may be treated by brushing the solution over the surface with a paint brush (fig. 423). Brushing does not damage or destroy latent impressions on surfaces of this type. Cardboard boxes may be slit down the edges and flattened out to permit easy placement under the light.
Fig. 423
[Fig. 423]
Wet paper should be handled with extreme care to prevent tearing. In treating very thin types of paper the solution is best applied with a cotton swab or brush.
Photographs, Photostats, and blueprints of any value should not be treated with silver nitrate, since the developed prints or stains cannot be removed without destroying them.
In working with silver nitrate, wear rubber gloves or handle all specimens with tweezers; avoid spilling it on clothing. It will cause dark brown stains on clothing, skin, and fingernails. Such stains are not easily removed. Areas of the skin subjected to prolonged contact are deadened, will turn black and peel.
If removal of silver nitrate prints (called "de-silvering") is desired,this may be accomplished by placing the specimen in a 2-percent solution of mercuric nitrate in a tray similar to that used for the silver nitrate.
To prepare a small amount of this solution, dissolve two-thirds of an ounce of mercuric nitrate crystals in 1 quart of distilled water and add one-third of a fluid ounce of nitric acid. Shake well. This solution, too, may be used several times before losing its strength and is not necessarily discarded after each use. It is not necessary to keep it in a dark bottle.
The specimen bearing silver nitrate prints is immersed in this solution until all traces of the prints disappear. It should then be rinsed thoroughly in water to remove all mercuric nitrate. If this is not done the paper deteriorates, becoming brittle and crumbly. A tray of distilled water may be used for rinsing or a tray of ordinary tap water changed several times during the rinsing. The specimen is then laid out flat to dry.
Wrinkles, such as are left in paper after ordinary drying, may be prevented by ironing with a moderately hot iron. An electric iron with a temperature control is desirable. If kept too hot it will scorch or wrinkle the paper somewhat. The bottom of the iron should be clean so that unremovable smudges will not be left on the paper.
No ill effects have been noted from working in the 2-percent mercuric nitrate solution with bare hands for very short periods, but it is a caustic solution and it is suggested that the specimens be handled with tweezers or that rubber gloves be worn if contact is prolonged.