The Science of Fingerprints Part 13

No set rule can possibly be devised to enable a cla.s.sifier to know with certainty where to draw the line when it is doubtful which cla.s.sification should be given such a print. Individual judgment is the only standard. The test is: _if the pattern, in the opinion of the cla.s.sifier, is rolled to only a normal width, it should be cla.s.sified as it appears. If it seems to be rolled to a width beyond the normal degree, it should be cla.s.sified as if rolled only to the normal degree_. Age, weight, size of fingers (as seen in the plain impressions), heaviness of the ridges, and experience of the technician in taking fingerprints are all factors in arriving at the correct conclusion. The necessity for exercising the utmost care in dealing with this type of pattern cannot be too highly emphasized.

[Ill.u.s.tration: 345]

[Ill.u.s.tration: 346]

The patterns in figures 345 and 346 also have a second loop near the edge of the impression. In these two patterns, however, the second loop is very near the delta and consequently will almost invariably appear even though not rolled to the fullest extent. The foregoing rule is not applied to this type of impression. Both are cla.s.sified as a whorl and referenced to a loop to take care of the rare contingency of nonappearance.

CHAPTER IV

_The Cla.s.sification Formula and Extensions_

_The cla.s.sification formula_

At this point it is necessary to mention that when prints are cla.s.sified, markings are indicated at the bottom of each finger block to reflect the type. The following symbols are used:

- Under the index fingers the appropriate capital letters should be placed for every pattern except the ulnar loop.

- Under all other fingers, the appropriate small letter should be placed for every pattern except the ulnar loop and the whorl as follows:

Arch a Tented Arch t Radial Loop r

- Ulnar loops in any finger are designated by a diagonal line slanting in the direction of the loop.

- Whorls in any finger are designated by the letter "W". The cla.s.sification formula may be composed of the following divisions:

1. Primary 2. Secondary 3. Subsecondary 4. Major 5. Final 6. Key

The positions in the cla.s.sification line for these divisions when completely applied are as ill.u.s.trated:

Key Major Primary Secondary Subsecondary Final -------------------------------------------------------------------------- Divisions Cla.s.sification Cla.s.sification Cla.s.sification

20 M 1 U IOI 10 -------------------------------------------------------------------------- L 1 U IOI

Second subsecondary cla.s.sification Key Major Primary Secondary Subsecondary Final -------------------------------------------------------------------------- Divisions Cla.s.sification Cla.s.sification Cla.s.sification

SLM --- MMS 4 O 5 U IOI 10 -------------------------------------------------------------------------- I 17 U IOI

THE PRIMARY CLa.s.sIFICATION: For the purpose of obtaining the primary cla.s.sification, numerical values are a.s.signed to each of the ten finger s.p.a.ces as shown in figure 347. Wherever a whorl appears it a.s.sumes the value of the s.p.a.ce in which it is found. s.p.a.ces in which types of patterns other than whorls are present are disregarded in computing the primary.

The values are a.s.signed as follows:

Fingers No. 1 and No. 2 16

Fingers No. 3 and No. 4 8

Fingers No. 5 and No. 6 4

Fingers No. 7 and No. 8 2

Fingers No. 9 and No. 10 1

[Ill.u.s.tration: 347]

LEAVE THIS s.p.a.cE BLANK| |s.e.x +--------------+ | |__________ |FBI No. | | |RACE +--------------+ |LAST NAME FIRST NAME MIDDLE NAME| -----------------------------|----------------------------------+---------- SIGNATURE OF PERSON |CONTRIBUTOR |ALIASES |HT. |WT.

FINGERPRINTED |AND ADDRESS | |(IN.)| | | |_____|____ | | |DATE OF -----------------------------| | |BIRTH RESIDENCE OF PERSON | | |__________ FINGERPRINTED | | |HAIR |EYES | | | | -----------------------------|--------------------------------------------- OCCUPATION |ARREST NUMBER|LEAVE THIS s.p.a.cE BLANK | | -----------------------------|-------------| SCARS AND MARKS |PLACE OF | |BIRTH | 29 |-------------|CLa.s.s__________________________ -----------------------------|CITIZENs.h.i.+P | 19 SIGNATURE OF OFFICIAL |DATE | _ | TAKING FINGERPRINTS | ||_|CHECK IF | | | NO CRIMINAL|REF.___________________________ | | RECORD IS | | | DESIRED | --------------------------------------------------------------------------- 1. RIGHT THUMB|2. RIGHT INDEX|3. RIGHT |4. RIGHT RING |5. RIGHT LITTLE | | MIDDLE | | |N 16| |N 8| [Ill.u.s.tration]|[Ill.u.s.tration]|[Ill.u.s.tration]|[Ill.u.s.tration]|[Ill.u.s.tration]

D 16| |D 8| |D 4 --------------------------------------------------------------------------- W | W | | W | --------------------------------------------------------------------------- 1. LEFT THUMB |2. LEFT INDEX |3. LEFT |4. LEFT RING |5. LEFT LITTLE N 4| | MIDDLE | | | |N 2| |N 1 [Ill.u.s.tration]|[Ill.u.s.tration]|[Ill.u.s.tration]|[Ill.u.s.tration]|[Ill.u.s.tration]

|D 2| |D 1| --------------------------------------------------------------------------- W | W | / | / | / ---------------------------------------------------------------------------

In figure 347, it will be observed that the odd fingers (Nos. 1, 3, 5, 7, 9) contain the letter D, and the even fingers (Nos. 2, 4, 6, 8, 10) contain the letter N. The D indicates that the values of these fingers relate to the denominator, the N that they relate to the numerator.

The summation of the numerical values of the whorl type patterns, if any, appearing in fingers 1, 3, 5, 7, 9, plus one, is the denominator of the primary. The summation of the values of the whorls, if any, in fingers 2, 4, 6, 8, 10, plus one, is the numerator of the primary.

Where no whorl appears in a set of impressions, the primary, therefore, would be 1 over 1. The 1 that is a.s.signed to the numerator and the denominator when no whorls appear is also added, for consistency, to the value of the whorls when they do appear. It will be understood why it was originally a.s.signed to the no-whorl group when it is considered how easily a zero might be confused with an O, which is the symbol used for an outer whorl tracing.

To obtain the primary for the prints in figure 347, the number of whorls appearing in the odd fingers is ascertained to be 2. Their positions are noted (1 in No. 1 and 1 in No. 7) and the values a.s.signed to whorls appearing in those fingers are added together (16 plus 2 = 18). To this sum the arbitrary 1 is added, giving us the total of 19, which const.i.tutes the denominator for this set of prints.

To get the numerator, it is ascertained that there are 3 whorls appearing in the even fingers (2, 4 and 6), the values of which are added together (16 plus 8 plus 4 = 28). To this sum the 1 is added, giving a numerator of 29, and a complete primary of 29 over 19.

By the word "whorl" is meant all types of whorls, including plain whorls, central pocket loops, double loops and accidentals. The tracing of the whorl does not enter into the determination of the primary.

The method of obtaining the primary can probably be shown best by ill.u.s.trations. For example, a.s.sume that there is a whorl in the right index finger only. The value of a whorl in this finger is 16. When 1 over 1 is added the resulting primary is 17 over 1. If a whorl appears in the right thumb and right index finger, the value is 16 over 16 plus 1 over 1 giving a primary of 17 over 17. If whorls appear in both index fingers, the value is 16 over 2 plus 1 over 1 giving a primary of 17 over 3. When whorls appear in both thumbs and both index fingers, the primary is 21 over 19 and is obtained by the addition 16 plus 4 plus 1 over 16 plus 2 plus 1. If whorls appear in all 10 fingers, the primary is 32 over 32 (16 plus 8 plus 4 plus 2 plus 1 plus 1 over 16 plus 8 plus 4 plus 2 plus 1 plus 1). It will be noted that the primary cla.s.sifications extend from 1 over 1 in the no-whorl group to 32 over 32 in the all-whorl group, providing 1,024 possible combinations. This does not mean that there are 1,024 even subdivisions of prints according to these primaries. Just as there is a preponderance of loops when the types of patterns are considered, there is also a preponderance of certain primaries, notably: the 1 over 1 primary, or no-whorl group; the 17 denominator; the 19 denominator; the 28 denominator, of which the 31 over 28 group is the largest; and the 32 denominator, including 2 large primary groups namely, 31 over 32 and 32 over 32. As a matter of fact, the 1 over 1 group, as a whole, contains over 25 percent of the total number of prints filed in the FBI. On the other hand, there are a number of primaries which rarely appear. It follows, therefore, that when a print is cla.s.sified in one of these larger groups it is necessary to complete the cla.s.sification to a greater extent than is necessary in the more unusual primaries, so that the group to be searched is small enough for convenience.

In connection with the counting of whorl values to obtain the primary, it might be noted that when the whorls outnumber the other patterns more speed can be achieved by counting those patterns and subtracting rather than by adding the whorls. This procedure should not be followed until enough experience is acquired so that it may be noted at a glance where whorls are not present.

The experienced cla.s.sifier can tell in what fingers whorls are present by a glance at a primary cla.s.sification. For example, a primary of 5 over 17 could mean that there are whorls in the thumbs only.

[Ill.u.s.tration: 348]

LEAVE THIS s.p.a.cE BLANK| |s.e.x +--------------+ | |__________ |FBI No. | | |RACE +--------------+ |LAST NAME FIRST NAME MIDDLE NAME| -----------------------------|----------------------------------+---------- SIGNATURE OF PERSON |CONTRIBUTOR |ALIASES |HT. |WT.

FINGERPRINTED |AND ADDRESS | |(IN.)| | | |_____|____ | | |DATE OF -----------------------------| | |BIRTH RESIDENCE OF PERSON | | |__________ FINGERPRINTED | | |HAIR |EYES | | | | -----------------------------|--------------------------------------------- OCCUPATION |ARREST NUMBER|LEAVE THIS s.p.a.cE BLANK | | -----------------------------|-------------| SCARS AND MARKS |PLACE OF | |BIRTH | 9 R |-------------|CLa.s.s__________________________ -----------------------------|CITIZENs.h.i.+P | 2 R SIGNATURE OF OFFICIAL |DATE | _ | TAKING FINGERPRINTS | ||_|CHECK IF | | | NO CRIMINAL|REF.___________________________ | | RECORD IS | | | DESIRED | --------------------------------------------------------------------------- 1. RIGHT THUMB|2. RIGHT INDEX|3. RIGHT |4. RIGHT RING |5. RIGHT LITTLE | | MIDDLE | | | | | | [Ill.u.s.tration]|[Ill.u.s.tration]|[Ill.u.s.tration]|[Ill.u.s.tration]|[Ill.u.s.tration]

| | | | --------------------------------------------------------------------------- | R | | W | --------------------------------------------------------------------------- 1. LEFT THUMB |2. LEFT INDEX |3. LEFT M|4. LEFT RING |5. LEFT LITTLE 18| 10| MIDDLE I| I| 13 | | | | [Ill.u.s.tration]|[Ill.u.s.tration]|[Ill.u.s.tration]|[Ill.u.s.tration]|[Ill.u.s.tration]

| | | | --------------------------------------------------------------------------- / | R | / | W | / ---------------------------------------------------------------------------

THE SECONDARY CLa.s.sIFICATION: After the primary cla.s.sification, the fingerprints are subdivided further by using a secondary cla.s.sification. Before going into detail, it should be noted that after the primary is obtained the entire remaining portion of the cla.s.sification formula is based upon the arrangement of the impressions appearing in the right hand as the numerator over the impressions appearing in the left hand as the denominator. The arrangement of the even over the uneven fingers is discarded after the primary is obtained. The secondary cla.s.sification appears just to the right of the fractional numerals which represent the primary. It is shown in the formula by capital letters representing the basic types of patterns appearing in the index fingers of each hand, that of the right hand being the numerator and that of the left hand being the denominator (fig. 348). There are five basic types of patterns which can appear.

1. Arch A 2. Tented Arch T 3. Radial Loop R 4. Ulnar Loop U 5. Whorl W

[Ill.u.s.tration: 349]

LEAVE THIS s.p.a.cE BLANK| |s.e.x +--------------+ | |__________ |FBI No. | | |RACE +--------------+ |LAST NAME FIRST NAME MIDDLE NAME| -----------------------------|----------------------------------+---------- SIGNATURE OF PERSON |CONTRIBUTOR |ALIASES |HT. |WT.

FINGERPRINTED |AND ADDRESS | |(IN.)| | | |_____|____ | | |DATE OF -----------------------------| | |BIRTH RESIDENCE OF PERSON | | |__________ FINGERPRINTED | | |HAIR |EYES | | | | -----------------------------|--------------------------------------------- OCCUPATION |ARREST NUMBER|LEAVE THIS s.p.a.cE BLANK | | -----------------------------|-------------| SCARS AND MARKS |PLACE OF | |BIRTH | 1 R |-------------|CLa.s.s__________________________ -----------------------------|CITIZENs.h.i.+P | 1 aU SIGNATURE OF OFFICIAL |DATE | _ | TAKING FINGERPRINTS | ||_|CHECK IF | | | NO CRIMINAL|REF.___________________________ | | RECORD IS | | | DESIRED | --------------------------------------------------------------------------- 1. RIGHT THUMB|2. RIGHT INDEX|3. RIGHT |4. RIGHT RING |5. RIGHT LITTLE | | MIDDLE | | | | | | [Ill.u.s.tration]|[Ill.u.s.tration]|[Ill.u.s.tration]|[Ill.u.s.tration]|[Ill.u.s.tration]

| | | | --------------------------------------------------------------------------- | R | | | --------------------------------------------------------------------------- 1. LEFT THUMB |2. LEFT INDEX |3. LEFT M|4. LEFT RING |5. LEFT LITTLE 18| 10| MIDDLE I| I| 13 | | | | [Ill.u.s.tration]|[Ill.u.s.tration]|[Ill.u.s.tration]|[Ill.u.s.tration]|[Ill.u.s.tration]

| | | | --------------------------------------------------------------------------- a | / | / | / | / ---------------------------------------------------------------------------

SECONDARY CLa.s.sIFICATION (SMALL-LETTER GROUP): Prints with an arch or tented arch in any finger or a radial loop in any except the index fingers const.i.tute the small-letter group of the secondary cla.s.sification. Such "small letters," with the exception of those appearing in the index fingers, are brought up into the cla.s.sification formula in their proper relative positions immediately adjacent to the index fingers (fig. 349). A dash is used to indicate the absence of each small letter between the index fingers and another small letter or between two small letters, as

1 aUa-t 1 aU-t.

------- and ------ 1 R-a 1 U-a