As an expert, it is essential to take a clear print from the client for different purposes such as for PCC, and for compression and analysis of fingerprints in different cases. It's not difficult to get good, clear fingerprints. An excellent fingerprint on the fingerprint card should be dark grey in color and devoid of smudges in order to be identified. To get good prints, all you need to do is practice.
The first step is to get the sign of the individual on the fingerprint card. After that, you have to wash the person’s hand to get rid of any filth. Do check for lint on the fingers from towels used to dry the hands.
Inking: the second step is to ink the fingerprint to take a print on the fingerprint card. An expert may come across a variety of inking procedures. The most frequent are the ink and slab method, the porelon pad, and the inkless system. For all three approaches, the method of rolling fingerprints is the same.
Rolled impressions are created by rolling the finger or thumb from one nail edge to the next. They are made to show the entire friction surface of the finger or thumb, from the tip to one-quarter inch below the first joint. The larger surface of the fully rolled impression not only allows accurate classification but also gives more points for comparison.
There is a specific method of rolling the subject's fingers or thumbs in the ink and onto the fingerprint card to ensure a good impression.
The basic premise is to roll the finger of the right hand in the clockwise direction and the finger of the left hand in an anti-clockwise direction in the inked tile/ink pad/fingerprint scanner. Thumbs should be rolled in opposite directions of the fingers.
If your fingerprint is taken by the fingerprint expert or other authority, he should grasp the subject's hand and ensure that the finger to be printed is stretched. The rolling of the fingers should be in a single movement with only enough pressure applied. Light pressure will leave the partial and illegible print and too much pressure will leave a smudged and over-inked print. And in both cases, it will be difficult for the authority to identify the fingerprint. The person who is being fingerprinted should be instructed to look away from the fingerprint card and not to "facilitate" the roll in any way. In this way, smudging will be reduced, and a clear imprint will be created.
Plain Print: Simply press the four fingers on the card at a small angle to make a plain impression. They should be a one-quarter inch below the first joint with the points exposed. Thumbs are then printed by simply re-inking them and pressing them against the plain finger impressions on the block space provided separately in the fingerprint card. Plain impressions are used to validate the order of rolled impressions and to demonstrate certain properties that can be distorted in rolled prints. The fingers of the person should be stiff and straight. The wrist and the hand should be level. The individual taking the prints should use one hand to grip the wrist and the other hand to press the fingers onto the cards.
A case may necessitate the use of additional procedures in addition to fingerprints. In the next paragraphs, we'll go over a few of them.
Photographic Print: A highly detailed print is produced using glossy photographic print paper and a photographic developer. It can only be used for comparative purposes when a print's fine detail is necessary. The developer is lightly applied to the fingertips before being rolled onto the photographic paper. The paper is then immersed in a fixing bath for about 30 seconds before being washed like a regular image.
Palm Print: Because the entire hand leaves a distinct impression, it may be essential to get palm prints from a subject, and these impressions may be located on evidence or at a crime scene. The most common issue with palm prints is that the hollow region of the palm is frequently left unprinted. Wrapping printing paper around a tubular item and then placing the heel or base of the subject's palm on the tubular object and rolling the print in a pulling motion from the heel of the hand to the fingers is the ideal method for recording palm prints.
Major Case Prints: These are created throughout the course of an investigation into a serious crime. Because the side of the hand is printed, they are frequently useful in forgery investigations. (This depicts the impression of a hand in the posture of writing.) All aspects of the hand, including the tips, palm, sides of the fingers, and sides of the palm, are effectively printed. The same processes can be used to generate prints of the feet if necessary.
Obtaining an excellent set of prints might be difficult. In this part, we'll look at a few of these issues.
Skin Nature: if the nature of the skin surface is rough and dry rubbing oil or creams on the ends of the fingers will frequently make them malleable and supple enough to form clear un-smudged prints. If the skin is oily then they should rub the fingers against cloth to remove the excess oil in order to avoid the smudging of the print. If the ridges are fine and small, and the skin is soft—as it often is with children or women—holding ice against the fingers will help.
Deformed fingers or hands: If the hands and fingers of the subjects are so deformed that the normal printing method cannot be used, then prints can be made by applying the ink directly to the fingers with a spatula or small roller. A square piece of paper is rotated around the finger. When a satisfactory print has been made, this square is then taped to the appropriate box of the fingerprint card.
Excessive Perspiration: Some inked imprints will be indistinct due to the subject's high sweat. After wiping each finger with a cloth, ink and roll the finger on the fingerprint card right away. With each finger, repeat the process. It's also possible to use alcohol, benzene, or another drying chemical to wipe the fingertips.