MIDTERM
MIDTERM
MIDTERM
Identification of fingerprints relies on pattern matching followed by the detection of certain ridge
characteristics, also known as Galton details, points of identity, or minutial points with a reference print,
usually an inked impression of a suspect’s print. The light areas of fingerprints are called ridges while the dark
1. Ridge Surface
= Ridge – the elevated or hill-like structure / the black lines with white dots.
= Furrows – the depressed or canal-like structure / the white space between ridges. 2. Sweat Pores
3. Sweat Duct
4. Sweat Gland
1. Friction ridge breath – the width of the friction ridges varies in different areas as well in different
2. Ridge units and pores – pore ducts open along the top of the friction ridges. Each ridge unit has one
sweat gland and a pore opening randomly somewhere on its surface. Eccrine gland contains
3. Specific ridge path – the friction ridges have been compared to corduroy, but unlike corduroy they are
not continuous in nature. The path taken by the ridges may branch, start or stop, turn, twist, or
4. Incipient friction ridges – narrow and often fragmented ridges may appear between normal friction
ridges. These are called incipient, rudimentary, or nascent ridges. They differ from the typical ridge
same direction. Imbrication ridges vary among individual and even the regions of volar areas where
6. Overall friction ridge pattern – the friction ridges form pattern on the volar surface. The most
common are concentric, looping, or arching formations. Friction ridges patterns also enhance the
ability of volar skin to avoid slippage. The pattern also enhances tactile sensitively due to the
increased friction.
Ridge Characteristics
Identification of fingerprints relies on the pattern matching followed by the detection of certain ridge
characteristics, also known as Galton details, points of identity, or minutial points with a reference print,
1. Bifurcating Ridge – a single ridge that splits into two forming a “Y” shape.
2. Diverging Ridges – two ridges running side by side and suddenly separating, one ridge going the one
3. Converging Ridge – these are two ridges that meet at a point forming an angle.
4. Recurving Ridge – a single ridge that curves back in the direction from where it started.
A ridge ending is one of a long island. The island is long enough that the ends are not easily recognized as being
A bifurcation is where the ridge path divides forming a Y shape with legs having the same length.
A ridge dot, one ridge unit, is the shortest of all island and the building block of the friction ridge.
An island in strict usage is the ultimate abbreviation of ridge structure, a unit bearing but one sweat pore
A lake (enclosure) is a bifurcation which does not remain open but which the legs of the bifurcation after
running alongside for a short distance come together to form a single ridge once more.
A spur is where the ridge path divides and one branch comes to an end (leg is shorter).
An incipient ridge is an unusual type of ridge found in small percentage of patterns. They are short, narrow and
badly formed ridges between two well-formed and full-bodied ridges which is frequently interrupted.
A short ridge has two or more ridge units with both ends easily recognized as being from the same island.
A trifurcate ion is when two bifurcations develop next to each other on the same ridge, a unique formation.
A ridge crossing is the point where two ridges cross each other forming an “X” formation.
Type lines or skeleton of pattern are two innermost ridges which start parallel, diverge, and surround or tend
to surround the pattern area. They serve as basic boundaries of a fingerprint pattern.
The pattern area is the part of a fingerprint pattern in which the core, delta and ridges appear enclosed by
The core and delta are the focal points of fingerprint patterns except in arch patterns.
The core is a point on the ridge formation usually located at the center or heart of the pattern. The core is
A delta or outer terminus is a point on the ridge formation at or directly in front or near the center or the
2. When the innermost sufficient contains an uneven number of rods rising as high as the shoulders, the
core is placed upon the end of the center rod whether it touches the looping ridge or not.
3. When the innermost sufficient recurve contains an even number of rods rising as high as the shoulder,
the core is placed upon the two center rods being treated as though they were connected by a
recurving ridge.
1. The delta may not be located at a bifurcation which does not open towards the core.
2. When there is a choice between a bifurcation and another type of delta equally close to the point of
3. When there is a series of bifurcations opening towards the core at the point of divergence of the two
type lines, the bifurcation nearest to the core is chosen as the delta.
4. The delta may not be located in the middle of the ridge running between the type lines toward the
5. If the ridge enters the pattern area below the divergence of the type lines, the delta must be located
Forms of Deltas
1. Dot
2. Bifurcation
3. Ending ridge
Ridge Counting – It refers to the process of counting the ridges that touch or cross an imaginary line drawn
Ridge Tracing – It is the process of tracing the ridge that emanates from the lower side of the left delta to
A. LOOPS
1. RADIAL LOOP – A loop is radial when the opening end of the loop ridge points in the direction of
2. ULNAR LOOP – A loop is ulnar when the opening end of the loop ridge points in the direction of
B. WHORLS
1. PLAIN WHORL – A fingerprint pattern in which there are two deltas in which at least one ridge
makes a turn through one complete circuit. Imaginary line drawn between the two deltas must
touch or cross at least one of the circuiting whorl ridges within the pattern area.
2. CENTRAL POCKET LOOP WHORL – A fingerprint pattern which form the most
part of a loop, but which has a small whorl inside the loop ridges, sometimes called a “composite
pattern” which means that it is made up of two patterns in one, a whorl inside a loop.
It has two deltas, one which appears at the edge of the pattern area as in loop and one which
shows inside the pattern area just below the counterpart ridges.
3. DOUBLE LOOP WHORL – A fingerprint pattern consisting of two separate and distinct loop
formation. One of the loop surrounds or overlaps the other, also called “composite patterns” like
the central pocket loop whorl. It arises from the fact that these patterns are a composite or
combination of two patterns in one with two cores and two deltas.
The two loops in a double loop whorl need not comply with all the requirements for a loop pattern
that no ridge count is necessary for both loops in the formation. The two loops do not have the
same length nor the same size. All that is required is that there be two separate and distinct loop
types of pattern except in plain arch. It can be a combination of a loop and a whorl, a loop and a
central pocket loop whorl or any combination of two different loops and whorl patterns.
Like the central pocket loop whorl and the double loop whorl, some authors call accidental whorl
“composites”.
Unlike the other whorl type patterns, an accidental whorl can be having two, three or four deltas.
1. PLAIN ARCH – A fingerprint pattern in which the ridges enter on one side of the pattern and
flow towards the other side, with a rise in the center with not more than one of the four
requisites for a loop and with no recurving ridge, no angular formation, and no upward trust.
2. TENTED ARCH – A variety of arch family but their ridge formation are not so simple as those of
a plain arch, also considered “transitional pattern” between a plain arch and a loop.
QUESTIONABLE PATTERNS – These are patterns that do not have definite identification. These patterns
The figure below has two loop formations. The one on the left, however, has an appendage abutting upon the
shoulders of its recurve at a right angle. The left portion of the impression, therefore, is of tented arch type.
The combination of two different types of patterns would be classified in the whorl group (accidental, but this
impression has only one delta). The right portion of the pattern detail contains a true loop which fulfills all the
loop requirements. In the choice existing between a tented arch and a loop, preference is given to the loop
The classification of fingerprints into distinct groups based on general similarities allows the fingerprint
examiner to search for an unidentified fingerprint within the specific section of the fingerprint file rather
than having to search the whole file. There are numerous classification systems in use throughout the world
today. These systems are all based on the Purkinje, Galton, Vucetich and Henry System with Modifications and
Classification refers to the formula derived for the complete set of ten fingerprint patterns or the
Primary Classification
1. Primary classification = PC
2. Secondary Classification = SC
5. Major Classification = MC
6. Key Classification = KC
For the purpose of obtaining the primary classification, numerical values are assigned to each of the ten finger
spaces whenever a whorl appears, it assumes the value of the space in which it is found. Spaces in which types
of patterns other than whorls are present are disregarded in computing the primary.
Whorls in the primary are also known as numerical patterns, while loops and arches are the non-numerical
patterns.
The fingers in a set of print are numbered in its natural sequence, beginning with the thumb of the right hand
The fingers are grouped into two: the denominator and numerator as follows:
The numerator is the total numeral value of whorls appearing in any of the even numbered fingers (2, 4, 6, 8,
10), while the denominator is the total numerical value of whorls appearing in any of the odd numbered fingers
(1, 3, 5, 7, 9). An arbitrary count of one is always added to the sum of the numerator and the denominator to
When no whorl appears in a set of fingerprints, there can be no numerical value, therefore the primary
classification becomes zero-over-zero. When all fingers and thumbs contain all whorls, the numerical value of
the patterns is the maximum total value which is thirty – two over thirty – two. Secondary Classification
This 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.
1. Plain Arch A
2. Tented Arch T
3. Radial Loop R
4. Ulnar Loop U
This is placed on the classification line just to the right of the secondary. Ridge counts are translated into
(Outer) for the loops. The whorl tracings are brought up as “I” (Inner), “M” (Meeting) or “O” (Outer) of the
sub-secondary namely:
Right index finger – No.2
For the purpose of infirmity, a definite number of ridge count is established and is assigned to each of the
fingers involved. This designated number of ridges is the same of both hands, but varies for different fingers.
Sub-Secondary Classification
Three or more ridges above the right delta is “I” (Inner) tracing, zero, one or two ridges is “M” (Meeting)
tracing, and three or more ridges below the right delta is “O” (Outer) tracing.
1. Tracing always begins at the extreme left delta and stops at the point directly in front of the right
delta.
2. An uninterrupted ridge can be traced from the left delta to the right delta.
3. When tracing suddenly ends, the tracing is continued on the ridge below it.
4. A ridge must definitely end before the tracing may be continued on the ridge below
it.
5. When the ridge bifurcates, the tracing is continued on the lower branch of the bifurcation.
6. When the delta is a dot, the tracing begins on the type line which is the ridge immediately below the
delta.
The small letter group in the Sub-secondary classification consist of plain arch (a), tented arch (t), and radial
loop (r). Such small letters with the exception of those appearing in the index fingers, are brought up into the
classification formula in their proper relative positions immediately adjacent to the index fingers. A “dash” (-)
is used to indicate the absence of each small letter between the index fingers and another small letter or
between two letters. Thus, if a radial loop appears in the right thumb, the small letter “r” would be brought up
in the numerator column of the classification formula and placed just to the left of the capital letter
representing the index finger. Similarly, if a plain arch or tented arch or a radial loop would appear in the
middle, ring or little finger of the hand, the small letter representing such a pattern would be placed on the
classification line to the right of the secondary in the numerator column if the letter is present in the right
Final Classification
This is obtained upon the ridge count of the loop in the right little finger or both the little fingers. It is
Rules:
1. If a loop does not appear in the right little finger, a loop in the left finger may be used. It is then
2. If no loops appear in the little fingers, a whorl may be used to obtain a final from left delta to core if
in the right hand and from right delta to core if in the left hand. If there are two or more cores
(usually in the accidental whorls), the ridge count is made from left delta (right hand) or right delta
(left hand) to the core which is the least number of ridges distant from the delta.
In double loop whorl, it is counted from the delta to the core of the upright loop. Where loops of a
double loop are horizontal, the nearest core is used. Should both little fingers be plain or tented