Introduction to Classification Systems
As with any method of classification, the purpose of classifying fingerprints is to establish a set protocol to utilize for searching, filing, and comparison purposes. This protocol provides an orderly method with which to go from the general to the specific. As an example, how would one begin to search for a fingerprint pattern if that pattern has not been cataloged? Questions would certainly arise: What type of pattern are we trying to locate? Is the pattern a loop, whorl, or arch? Is there a specific flow to the pattern? If the pattern is a loop, is it a large or small count loop flowing to the left or to the right? If the pattern is a whorl, does it have an outer, inner, or meet trace value? Some of these basic questions give us direction to understand the need to have a method by which to search.
Henry with FBI Extension
One of the first, and certainly the most noted, of the classification systems was a system named after Sir Edward Henry. This identification system, when originally developed and implemented, consisted of four parts: primary, secondary, subsecondary, and final. The system has since undergone changes and now includes an FBI (U.S. Federal Bureau of Investigation) extension, which changes the original configuration from four to six categories. There is a seventh category, if a second subsecondary is used. Since the introduction of technology and various automated fingerprint identification (AFIS) systems, this method has come to be known as the manual method. In later parts of the book, AFIS systems are discussed.
As with any process that is newly introduced, with the Henry system of classificationbeing no exception, the need to practice and understand the system is tantamount. The current components of the Henry system are:
An example of the form of the Henry classification is shown in the following:
Where does the information for classification come from? The fingerprint card gives us the necessary information. Knowing how to read and insert appropriate information onto the fingerprint card is important. The process of inserting information onto the card is known as blocking the card. Figures 4.1-4.3 show examples of fingerprint cards.
Blocking the card consists of inserting the appropriate information, consisting of numbers, letters, and symbols in the appropriate places on the card. Below is an example of the layout and position of the fingers on the fingerprint card.
Based on the fingerprints and their interpretation, the following information should be placed on the card in the appropriate places.
Figure 4.1 Fingerprint card (tenprint).
6. Reference if necessary (giving an alternative).
It should be noted that the right thumb is always finger number 1, and the left little finger is finger number 10. Also note that fingers that oppose are opposite to each other on the card, for example, 1/6, 2/7, 3/8, 4/9, 5/10.
For the purposes of the classification, the right hand and even number fingers go above the line. The left hand and odd number fingers go below the line.
To begin the process of manual classification, one starts with the Primary. Remember, Primary is the numeric value of the finger where a whorl appears. Any type of whorl is assigned a value. Ridge tracing does not enter into the primary classification. The numeric value was established with the advent of the Henry system. Whatever finger the whorl appears on,
Figure 4.2 Fingerprint card (left hand).
that finger assumes that value of the square. Upon adding up the numbers, always add 1 to the value (the numeric chart appears below). Even number fingers, 2, 4, 6, 8, and 10, are registered above (numerator) the classification line. Odd number fingers 1, 3, 5, 7, and 9, are registered below (denominator) the line.
Figure 4.3 Fingerprint card (right hand).
As an example of how the primary is completed, look at the card below. Whorls appear on fingers 2, 8, and 10. The value would be 16 + 2+1 = 19+1 for a primary value of 20, which would go above the line (numerator), as those are even number fingers. Whorls also appear in fingers 3, 5, and 7. The value would be 8 + 4 + 2=14+1 for a primary of 15, which would go below the line (denominator), as those are odd number fingers.
There are 1,024 different combinations of whorl values. Where all whorls appear on the card, the primary classification will be 32 over 32. Where no whorls appear on the card, the primary classification will be 1 over 1.
The Secondary portion of the classification indicates the pattern type of the index fingers and is always indicated by a capital letter.
. W = Whorl
• U = Ulnar loop
The designation of the capital letters will always be right hand over left hand on the classification line. The secondary portion of the classification will be indicated by placing the information immediately to the right of the primary classification. See the example below.
There is also a secondary, small letter grouping. Some say the small letter grouping is part of the subsecondary. In any event, whenever there is a small letter grouping in the classification, the secondary and subsecondary become one in the same. Let us first look at the small letter groupings. Whenever an arch, tented arch, or radial loop appears in other than the index fingerprints, those patterns are indicated by a small letter:
The small letter groups should appear next to the capital letter of the secondary in the sequence in which they occur. For example, if the fingerprint of an index finger is a whorl, and that of the middle finger is a tented arch, the small t would then be placed to the immediate right of the whorl in order of its appearance on the card. If the thumb were an arch, for example, the small letter indicator would then appear to the immediate left of the index finger. In the secondary classification, the index finger can be seen as the anchor and all small letter group patterns appear to the right or left of the index finger (see the example below).
When other patterns appear on the card along with the small letter groups, (U, W) they are indicated by a hyphen (-).
When two or more of the small letters occur next to each other, they are indicated by a number with the letters (see the examples below).
Where there is a small letter group in the secondary, the subsecondary and major divisions are dispensed with. It should also be noted that approximately 7 to 10 percent of all patterns are small letter types.
Small letter groups can lend themselves to confusion. Remember, the small letter groups are indicated in the classification where they appear on the card with the index finger as the anchor indicated by a capital letter.
The Subsecondary division of the classification is the grouping of ridge count and/or whorl trace symbols for the index, middle, and ring fingerprints appearing on the card. For classification purposes, the right hand is indicated above the line, the left hand is indicated below the line. The subsecondary division appears to the immediate right of the secondary division on the card. The subsecondary is indicated by a letter.
To determine which symbol will be used to indicate the ridge count for a loop pattern, a conversion of ridge counts into a letter must be done and that letter placed onto the classification. The conversion chart is: