● When an impression is so scarred that neither the general type of pattern nor the ridge tracing or count can be determined with reasonable accuracy, the impression should be given both the general type value and the subclassification value of the corresponding finger of the other hand.● When an impression is partially scarred, i.e., large scars about the core so that thegeneral typecannot be determined withreasonable accuracy, but the ridges allow reasonably accurate subclassifications by ridge tracings or counting, the impression should be given the primary value of the pattern of the corresponding finger and the subclassification value as indicated by the ridges of partially scarred impressions.● When an impression is partially scarred and the general type of pattern can be determined with reasonable accuracy, but the ridges cannot be traced or counted so as to fall within the proper subsecondary classification, the impression should be given the ridge count or tracing value of the corresponding finger of the other hand, if the corresponding finger is of the same general type. If the corresponding finger is not of the same general type, the scarred impression should be given the probable value and referenced to all other possibilities.● When an impression is so scarred that neither the general type of pattern nor the ridge tracing or count can be determined with reasonable accuracy, and it so happens that the corresponding finger of the other hand is similarly scarred, both patterns are given the arbitrary value of whorls with meeting tracings.
● When an impression is so scarred that neither the general type of pattern nor the ridge tracing or count can be determined with reasonable accuracy, the impression should be given both the general type value and the subclassification value of the corresponding finger of the other hand.
● When an impression is partially scarred, i.e., large scars about the core so that thegeneral typecannot be determined withreasonable accuracy, but the ridges allow reasonably accurate subclassifications by ridge tracings or counting, the impression should be given the primary value of the pattern of the corresponding finger and the subclassification value as indicated by the ridges of partially scarred impressions.
● When an impression is partially scarred and the general type of pattern can be determined with reasonable accuracy, but the ridges cannot be traced or counted so as to fall within the proper subsecondary classification, the impression should be given the ridge count or tracing value of the corresponding finger of the other hand, if the corresponding finger is of the same general type. If the corresponding finger is not of the same general type, the scarred impression should be given the probable value and referenced to all other possibilities.
● When an impression is so scarred that neither the general type of pattern nor the ridge tracing or count can be determined with reasonable accuracy, and it so happens that the corresponding finger of the other hand is similarly scarred, both patterns are given the arbitrary value of whorls with meeting tracings.
In figure 355, the pattern is entirely obliterated. It could have been a small whorl, a small ulnar or radial loop, an arch, or a tented arch. If the opposite finger were an arch or tented arch or whorl, this impression would be classified as arch, tented arch, or whorl (with the same tracing). If the opposite finger were a small-count loop, this would be classified as a loop of the same count. If the opposite finger were a large-count loop, this impression would be given the count of the opposite finger even though it could never have had that count. If the oppositefinger were scarred in the same fashion or were amputated or missing, both impressions would be classified as whorls with meeting tracings.
Fig. 355
[Fig. 355]
In figure 356, the general type of the pattern could have been loop (ulnar if in the right hand) or whorl. 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
[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. If the opposite finger were a loop with a count of from 6 to 17, thisimpression would be given that count. If the count of the opposite loop were less or more than 6 to 17, the count for this finger would be given I or O in the subsecondary classification depending upon whether the opposite finger was I or O, but would not be given less than 6 nor more than 17 counts as its possibility is limited to those counts.
Fig. 357
[Fig. 357]
A pattern with a scar similar to either scar in figures 358 and 359 would always be given a loop as it could be seen readily that there was no possibility of its having been any other type of pattern.
Fig. 358
Fig. 359
[Figs. 358-359]
When one or more amputations appear upon a fingerprint card, it may be filed separately from those having no amputations in order to facilitate searching. It is to be noted that before it may be filed in the amputation group, the card must contain a definite and unequivocal statement or marking by the contributor to the effect that a certain finger or fingers have been amputated or were missing at birth. This prevents the appearance on later cards of impressions of fingers thought to have been amputated but which in reality were merely injured and bandaged when previous prints were submitted.
If one finger is amputated, it is given a classification identical with that of the opposite finger, including pattern and ridge count, or tracing, and referenced to every other possible classification.
If two or more fingers are amputated, they are given classifications identical with the fingers opposite, with no additional references.
If two amputated fingers are opposite each other, both are given the classification of whorls with meeting tracings.
When a fingerprint card bearing a notation of fingers missing at birth is classified, the missing fingers should be treated as amputations in that they are given the identical classifications of the opposite fingers and are filed in the amputation group. As these fingers are missing from a prenatal cause, they would have always received the identical classification of the opposite finger on any previous occasion.
If all 10 fingers are amputated or missing at birth, the classification will be
If both hands are amputated or missing at birth, the footprints should be taken as they, too, bear friction ridges with definite patterns. A footprint file is maintained by the FBI for identification purposes in instances where the subject has all fingers amputated or missing at birth.
Partially amputated fingers often present very complex problems and careful consideration should be given to them. The question often arises as to the appropriate groups in which they should be filed, i.e., amputations or nonamputations. As no definite rule may be applied, it is a matter of experience and judgment as to their preferred classification.
In those instances in which a partially amputated finger has half or more than half of the pattern area missing, it is given the classification of the opposite finger. It will be filed in the amputation group under the classification of the opposite finger and reference searches should be conducted in all possible classifications in the nonamputation groups. If two or more of the fingers are amputated in this manner, they are given the classification of the opposite fingers only and are governed by the rules concerning amputations.
Generally, a "tip amputation," or one which has less than half of the first joint amputated, will always be printed in the future. Therefore, a partially amputated finger with less than half of the pattern area missing is classified as it appears and is referenced to the opposite finger. It will be filed in the nonamputation group and reference searches should be conducted under the classification of the opposite finger, and in the amputation group. It must be referenced this way even though it never could have originally had the classification of the opposite finger.
As noted in the chapter pertaining to "Problems in the Taking of Inked Fingerprints," an indication to the effect "recently injured, bandaged" is not sufficient to file a fingerprint card. It is obvious that a fingerprint card bearing these notations cannot be properly classified or filed. If the injury is temporary, and if possible, these prints should not be taken until after healing.
If fingers are injured to the extent that it is impossible to secure inked impressions by special inking devices, the unprinted fingers are given classifications identical with the classifications of the fingers opposite. If only one finger is lacking, reference searches should be conducted in every possible classification. If more than one finger is lacking, they should be given the classifications of the opposite fingers, but no referencesearches should be conducted. If there are two lacking, opposite each other, they should be classified as whorls with meeting tracings.
If, however, in the case of an injured finger, observation is made of the ridges of the finger itself and indicated on the print, this classification should be, insofar as it is possible, utilized. For example, a missing impression labeled "ulnar loop of about 8 counts" by the individual taking the prints, should be searched in the subsecondary as both I and O but should not be referenced as a pattern other than a loop. If the finger is used as the final, or key, it should be searched enough counts on each side of 8 to allow for possible error in the counting by the contributor using his naked eye.
The sequence must be arranged properly at all times to make possible the most accurate work. Prints are sequenced and filed in this order, according to:
I.Primary:
In the primary classification the denominator remains constant until all numerator figures have been exhausted from 1 to 32. All prints with the primary 1 over 1 are filed together. These are followed by 2 over 1, 3 over 1, 4 over 1, etc., until 32 over 1 is reached. The next primary is 1 over 2, then 2 over 2, etc., until 32 over 2 is reached. Eventually, through the use of each denominator figure and the elimination of each numerator over each denominator, the 32 over 32 primary will be reached.
Even in the smaller collections of fingerprints, it will be found that the groups which are arranged under the individual primaries filed in sequence, from 1 over 1 to 32 over 32, will be too voluminous for expeditious searching.
II.Secondary:
A. Secondary small-letter group:
Most intricate of all the individual sequences is the small-letter sequence. It is less difficult if the following method is used:
1. Sequence according to the patterns in the index fingers, grouped
When small letters are present, there are 25 possible combinations which can appear in the index fingers. They are as follows:
A T R U W- - - - -A A A A AA T R U W- - - - -T T T T TA T R U W- - - - -R R R R RA T U R W- - - - -U U U U UA T U R W- - - - -W W W W W
A T R U W- - - - -A A A A AA T R U W- - - - -T T T T TA T R U W- - - - -R R R R RA T U R W- - - - -U U U U UA T U R W- - - - -W W W W W
2. Within each group sequence:
a. The denominator, by—
(1) Count of the small letters (lesser preceding the greater).
(2) Position of the small letters (those to the left preceding those to the right).
(3) Type of small letter (sequence a, t, r).
b. The numerator, by—
(1) Count.
(2) Position.
(3) Type.
Thus
The following table represents the full sequence of the denominator of the group having A over A in the index fingers. The full sequence as listed may be used as the numerator for each denominator as set out below. Following the group with A over A in the index fingers is the group with T over A in the index fingers, the sequence being the same otherwise. Then R over A, U over A, A over T to rW3r over rW3r.
B. Secondary loop and whorl group:
When no small letters are present, there are 9 possible combinations which can appear in the index fingers. They are as follows:
R U W- - -R R RR U W- - -U U UR U W- - -W W W
R U W- - -R R RR U W- - -U U UR U W- - -W W W
At this point it is well to note that it may be preferable in some instances where small files are concerned to use only a portion of the classification formula in the filing sequence. In such cases, only those parts of the filing sequence which are necessary should be used along with the final and key.
III.Subsecondary:
The sequence of the subsecondary is as follows:
III IIM IIO IMI IMM IMO IOI--- --- --- --- --- --- ---III III III III III III IIIIOM IOO MII MIM MIO MMI MMM--- --- --- --- --- --- ---III III III III III III IIIMMO MOI MOM MOO OII OIM OIO--- --- --- --- --- --- ---III III III III III III IIIOMI OMM OMO OOI OOM OOO OOO,--- --- --- --- --- --- etc., to ---III III III III III III OOO
III IIM IIO IMI IMM IMO IOI--- --- --- --- --- --- ---III III III III III III IIIIOM IOO MII MIM MIO MMI MMM--- --- --- --- --- --- ---III III III III III III IIIMMO MOI MOM MOO OII OIM OIO--- --- --- --- --- --- ---III III III III III III IIIOMI OMM OMO OOI OOM OOO OOO,--- --- --- --- --- --- etc., to ---III III III III III III OOO
each numerator in turn becoming the denominator for the complete sequence of numerators as listed above.
IV.Major:
The following sequence is used when loops appear in both thumbs:
S M L S M L S M L- - - - - - - - -S S S M M M L L L
S M L S M L S M L- - - - - - - - -S S S M M M L L L
When whorls appear in both thumbs the sequence is:
I M O I M O I M O- - - - - - - - -I I I M M M O O O
I M O I M O I M O- - - - - - - - -I I I M M M O O O
When a whorl appears in the right thumb and a loop in the left, the sequence is:
I M O I M O I M O- - - - - - - - -S S S M M M L L L
I M O I M O I M O- - - - - - - - -S S S M M M L L L
When a loop appears in the right thumb and a whorl in the left, the sequence is:
S M L S M L S M L- - - - - - - - -I I I M M M O O O
S M L S M L S M L- - - - - - - - -I I I M M M O O O
V.Second Subsecondary:
The sequence for filing the second subsecondary is as follows:
SSS SSM SSL SMS SMM SML--- --- --- --- --- ---SSS SSS SSS SSS SSS SSSSLS SLM SLL MSS MSM MSL--- --- --- --- --- ---SSS SSS SSS SSS SSS SSSMMS MMM MML MLS MLM MLL--- --- --- --- --- ---SSS SSS SSS SSS SSS SSSLSS LSM LSL LMS LMM LML--- --- --- --- --- ---SSS SSS SSS SSS SSS SSSLLS LLM LLL, LLL,--- --- --- etc., to ---SSS SSS SSS LLL
SSS SSM SSL SMS SMM SML--- --- --- --- --- ---SSS SSS SSS SSS SSS SSSSLS SLM SLL MSS MSM MSL--- --- --- --- --- ---SSS SSS SSS SSS SSS SSSMMS MMM MML MLS MLM MLL--- --- --- --- --- ---SSS SSS SSS SSS SSS SSSLSS LSM LSL LMS LMM LML--- --- --- --- --- ---SSS SSS SSS SSS SSS SSSLLS LLM LLL, LLL,--- --- --- etc., to ---SSS SSS SSS LLL
each group of the numerator becoming in turn the denominator for the complete sequence of numerators as listed above.
VI.W C D X Extensions:
The sequence is as follows: Prints withc,d, orxin any finger other than the index fingers constitute the small-letter group. A sample of the sequence follows:
W cWc xWd WdxcW cWd xWx WxcdW cWx W2c WxdxW dWc Wcd W2xWc dWd Wcx cW2cWd dW Wdc cWcdWx xWc W2d cWcx
W cWc xWd WdxcW cWd xWx WxcdW cWx W2c WxdxW dWc Wcd W2xWc dWd Wcx cW2cWd dW Wdc cWcdWx xWc W2d cWcx
As may be readily seen, the sequence proceeds in the same fashion as the a, t, r, small-letter sequence.
VII. Special Loop Extension used by theFederal Bureau of Investigation:
The following is a partial sequence for filing this extension:
111 112 113 114 115 116 117--- --- --- --- --- --- ---111 111 111 111 111 111 111121 122 123 124 125 126 127--- --- --- --- --- --- ---111 111 111 111 111 111 111131 132 133 134 135 136 137--- --- --- --- --- --- ---111 111 111 111 111 111 111141 142 143 144 145 146 147--- --- --- --- --- --- ---111 111 111 111 111 111 111151 152 153 154 155 156 157--- --- --- --- --- --- ---111 111 111 111 111 111 111161 162 163 164 165 166 167--- --- --- --- --- --- ---111 111 111 111 111 111 111171 172 173 174 175 176 177 777.--- --- --- --- --- --- --- etc., to ---111 111 111 111 111 111 111 777
111 112 113 114 115 116 117--- --- --- --- --- --- ---111 111 111 111 111 111 111121 122 123 124 125 126 127--- --- --- --- --- --- ---111 111 111 111 111 111 111131 132 133 134 135 136 137--- --- --- --- --- --- ---111 111 111 111 111 111 111141 142 143 144 145 146 147--- --- --- --- --- --- ---111 111 111 111 111 111 111151 152 153 154 155 156 157--- --- --- --- --- --- ---111 111 111 111 111 111 111161 162 163 164 165 166 167--- --- --- --- --- --- ---111 111 111 111 111 111 111171 172 173 174 175 176 177 777.--- --- --- --- --- --- --- etc., to ---111 111 111 111 111 111 111 777
No matter how many of these divisions may be used, the order should remain the same; and no matter how many of these divisions are used, each individual group should be sequenced by:
VIII.Final:
Filed in numerical sequence from 1 out. For example, assume that there are 15 prints in a group having a final of 14. All of these should be filed together and followed by those prints in the same group having a final of 15, etc.
IX.Key:
All prints appearing in a designated final group are arranged by key in numerical sequence from 1 out. For example, assume that there are 5 prints in a group having a key of 14. All of these should be filed together and followed by those prints in the same group having a key of 15, etc.
When searching a print through the fingerprint files in order to establish an identification, it should be remembered that the fingerprint cards are filed in such a way that all those prints having the same classification are together. Thus, the print being searched is compared only with the groups having a comparable classification, rather than with the whole file.
After locating the proper group classification, the searcher should fix in his mind the one or two most outstanding characteristics of the patterns of the current print and look for them among the prints in file. If a print is found which has a characteristic resembling one upon the current print, the two prints should be examined closely to determine if identical. To avoid making an erroneous identification, the searcher should be exceedingly careful to ascertain that the prints being compared are identical in all respects before identifying one against the other.
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. The characteristics used to establish an identification are shown infigure 102.
The final and the key may be considered control figures for searching prints. They limit the number of prints it is necessary to search in a group to those prints having finals and keys closely related to the final and key of the print being searched.
Due to the possibility of visual misinterpretation, distortion by pressure, or poor condition of the ridge detail of the prints in file, it is advisable to allow a margin for such discrepancies. Except in cases where the ridge count of the final and/or key is questionable on the print being searched, the following procedure is used:
Of the prints within any group classification, only those prints are examined which have a final within 2 ridge counts on each side of the final of the print being searched. For example, if the print to be searched has a final of 17, all prints bearing a final 15 through 19 will be compared with it.
Within the final of any group classification, only those prints areexamined which have a key within 2 ridge counts on each side of the key of the print being searched. For example, if the print to be searched has a key of 20, all prints bearing a key of 18 through 22 will be compared with it.
Infigure 352, it will be noted that there are 17 ridge counts appearing in the right little finger and this number is used as the final. It will also be noted that there is a loop of 24 ridge counts in the right thumb and this number is used as the key inasmuch as it is the first loop. In this example, the print is searched in the group classification which has finals ranging from 15 through 19. Within this group of finals the prints which have keys ranging from 22 through 26 are examined.
Too much stress cannot be placed upon the necessity of referencing questionable patterns, whether it be in the interpretation of the type of pattern, the ridge count, or the tracing.
The factors which make it necessary are: variation in individual judgment and eyesight, the amount of ink used, the amount of pressure used in taking the prints, the difference in width of the rolled impressions, skin diseases, worn ridges due to age or occupations, temporary and permanent scars, bandaged fingers, crippled hands, and amputation.
For the highest degree of accuracy, all rolled impressions should be checked by the plain impressions, which generally are not distorted by pressure. This also helps prevent error caused by the reversal or mixing of the rolled impressions out of their proper order. For the same reason, as much of the counting and tracing should be done in the plain impressions as it is possible to do.
If there is any doubt as to which of two or more classifications should be assigned to a given pattern, it is given the preferred classification and reference searches are conducted in all other possible classifications. For example, if on a print with the preferred classification
it is questionable whether the left middle finger should be a plain arch, a tented arch, or a radial loop, the print is searched in the
group, and reference searches are conducted in the
and
groups. For further illustration, a print is given a preferred primary classification of
although the ridge detail on the right thumb is so formed as toresemble a whorl. The search is completed first in the preferred
primary classification and a reference search is then conducted in the
primary.
All ridge counts that are "line counts," i.e., when one more or one less count would change the designation of the loop from I to O or from S to M, etc., must be searched in both groups. For example, in a print classified
if the ridge count of the right middle finger is 10 and the count in the right thumb is 16 (as indicated by the key), the print would be searched first as classified, then reference searches would be conducted in the following groups:
When there is doubt concerning the tracing of a whorl, it should be treated in the same fashion. For example, if in the classification
doubt existed as to whether the tracing of the right thumb might not be a meeting tracing, the print would be searched as classified, and a reference search would be conducted in
If there is no doubt concerning the ridge count used for the final, it is enough to search out of the group only those prints containing a final within 2 ridge counts on each side of the final on the print being searched. When, however, there is doubt concerning the ridge count of the final, the print should be searched 2 ridge counts on each side of the two extremes of possibility. For example, if it were possible for a final to be 6, 7, 8, or 9 ridge counts, the print should be searched through that part of the group bearing finals of from 4 through 11.
The above explanation pertaining to the final also applies to the key.
All prints bearing amputations should be referenced to the necessary files containing prints other than amputations for reference searches.
In instances where only one finger is amputated, reference searches are conducted in all possible classifications, including all possible ridge counts or tracings. For example, a print containing the classification:
with the right index finger amputated, the left index finger being an ulnar loop, would be searched first in the amputation group for the classification, then reference searches would be conducted in the following groups in the nonamputation files:
All prints bearing unprinted or badly crippled fingers are filed in the nonamputation files, and reference searches are conducted in the amputation group.
For the purpose of determining if it is feasible to conduct reference searches in all possible classifications, the method of referencing amputations is applied to completely scarred patterns (Chapter titled "Scarred Patterns—Amputations—Missing at Birth"). For example, a print bearing the preferred classification:
with the left middle finger completely scarred, the right middle finger being an ulnar loop with a ridge count of 13, would be searched first in the group for that classification, then reference searches would be conducted in the following groups:
The referencing of partial scars is a problem in which many factors are present. A full explanation of the scars, their preferred classifications and their references is made in the chapter, "Classification of Scarred Patterns—Amputations—Missing at Birth."
When the age extension is utilized and a "Reference" group and a "Presumptive Dead" file are maintained, it is suggested that a general allowance of 5 years be considered to allow for a discrepancy in prints bearing the ages of 50 years or older.
In the files of the Federal Bureau of Investigation the various age groups are as follows:
Reference searches for the preceding groups are conducted in the following manner:
If no age is given, it should be searched first in the regular file and reference searches should be conducted in the "Reference" group and the "Presumptive Dead" file.
When separate male and female files are maintained, there may be doubt as to the sex of a subject due to a discrepancy between the sex indicated and the name and the description and picture. In such case try to determine the sex from the description and the size of the prints, then reference the print to the other file. A Photostat copy can be made and placed in the other file until the true sex can be determined.
The equipment required for taking fingerprints consists of an inking plate, a cardholder, printer's ink (heavy black paste), and a roller. This equipment is simple and inexpensive.
In order to obtain clear, distinct fingerprints, it is necessary to spread the printer's ink in a thin even coating on a small inking plate. A roller similar to that used by printers in making galley proofs is best adapted for use as a spreader. Its size is a matter determined by individual needs and preferences; however, a roller approximately 6 inches long and 2 inches in diameter has been found to be very satisfactory. These rollers may be obtained from a fingerprint supply company or a printing supply house.
An inking plate may be made from a hard, rigid, scratch-resistant metal plate 6 inches wide by 14 inches long or by inlaying a block of wood with a piece of glass one-fourth of an inch thick, 6 inches wide, and 14 inches long. The glass plate by itself would be suitable, but it should be fixed to a base in order to prevent breakage. The inking surface should be elevated to a sufficient height to allow the subject's forearm to assume a horizontal position when the fingers are being inked. For example, the inking plate may be placed on the edge of a counter or a table of counter height. In such a position, the operator has greater assurance of avoiding accidental strain or pressure on the fingers and should be able to procure more uniform impressions. The inking plate should also be placed so that the subject's fingers which are not being printed can be made to "swing" off the table to prevent their interfering with the inking process. A fingerprint stand such as that shown in figure 360 may be purchased from fingerprint supply companies. The stand is made of hardwood and measures approximately 2 feet in length, 1 foot in height and width. This stand contains a cardholder and a chrome strip which is used as the inking plate. Two compartments used to store blank fingerprint cards and supplies complete the stand. This equipment should be supplemented by a cleansing fluid and necessary cloths so that the subject's fingers may be cleaned before rolling and the inking plate cleaned after using. Denatured alcohol and commercially available cleaning fluids are suitable for this purpose.
Fig. 360
[Fig. 360]
The fingerprints should be taken on 8- by 8-inch cardstock, as this size has generally been adopted by law enforcement because of facility in filing and desirability of uniformity. Figure 361 shows fingerprints properly taken on one of the standard personnel identification cards from the Federal Bureauof Investigation. From this illustration, it is evident there are two types of impressions involved in the process of taking fingerprints. The upper 10 prints are taken individually—thumb, index, middle, ring, and little fingers of each hand in the order named. These are called "rolled" impressions, the fingers being rolled from side to side in order to obtain all available ridge detail. The smaller impressions at the bottom of the card are taken by simultaneously printing all of the fingers of each hand and then the thumb without rolling. These are called "plain" or "fixed" impressions and are used as a check upon the sequence and accuracy of the rolled impressions. Rolled impressions must be taken carefully in order to insure that an accurate fingerprint classification can be obtained by examination of the various patterns. It is also necessary that each focal point (cores and all deltas) be clearly printed in order that accurate ridge counts and tracings may be obtained.
Fig. 361
[Fig. 361]
[Enlarge]
In preparing to take a set of fingerprints, a small daub of ink should be placed on the inking glass or slab and thoroughly rolled until a very thin, even film covers the entire surface. The subject should stand in front of and at forearm's length from the inking plate. In taking the rolled impressions, the side of the bulb of the finger is placed upon the inking plate and the finger is rolled to the other side until it faces the opposite direction. 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.)
If consideration is given the anatomical or bony structure of the forearm when taking rolled impressions, more uniform impressions will be obtained. The two principal bones of the forearm are known as the radius and the ulna, the former being on the thumb side and the latter on the little finger side of the arm. As suggested by its name, the radius bone revolves freely about the ulna as a spoke of a wheel about the hub. In order to take advantage of the natural movement in making finger impressions, the hand should be rotated from the awkward to the easy position. This requires that the thumbs be rolled toward and the fingers away from the center of the subject's body. This process relieves strain and leaves the fingers relaxed upon the completion of rolling so that they may be lifted easily from the card without danger of slipping which smudges and blurs the prints. Figures 362 and 363 show the proper method of holding a finger for inking and printing a rolled impression.
Figs. 362-363
[Figs. 362-363]
The degree of pressure to be exerted in inking and taking rolled impressions is important, and this may best be determined through experience and observation. It is quite important, however, that the subject be cautioned to relax and refrain from trying to help the operator by exerting pressure as this prevents the operator from gaging the amount needed. A method whichis helpful in effecting the relaxation of a subject's hand is that of instructing him to look at some distant object and not to look at his hands. The person taking the fingerprints should stand to the left of the subject when printing the right hand, and to the right of the subject when printing the left hand. In any case, the positions of both subject and operator should be natural and relaxed if the best fingerprints are to be obtained.
To obtain "plain" impressions, all the fingers of the right hand should be pressed lightly upon the inking plate, then pressed simultaneously upon the lower right hand corner of the card in the space provided. The left hand should be similarly printed, and the thumbs of both hands should be inked and printed, without rolling, in the space provided. Figures 364 and 365 show the correct method of taking plain impressions of the fingers and thumbs.
Figs. 364-365
[Figs. 364-365]
From time to time various problems arise concerning the taking of inked impressions. It is believed that these problems can be divided into four phases: