What is the comparison of fingerprints?

Fingerprint comparison is one of the most famous forensic techniques used in the investigation of criminology and the crime scene. The surface of the skin on the inside of the fingers and the palm is covered with small combs, which form a unique formula for every person - even the same twins have different fingerprints - and these patterns remain unchanged during life. The potential glands in the fingers secrete fluid containing water, salts such as sodium chloride, lipids and amino acids that leave the pattern in the comb pattern on the surfaces that touched the finger. While the water evaporates relatively quickly in most circumstances, other components may persist for a long time, so that the formula that, if it can be restored and analyzed, will uniquely identify this person. Fingerprints found at the crime scene can be compared against those who are suspected or in the database; However, before comparing fingerprints, prints must be renewed and a suitable proalysis.

Many techniques are used in OTIDischarges to get suitable pictures from prints left at the crime scene. Fingerprints can be clearly visible on the surface such as glass, or it may be the impression of some soft material; In these cases, everything that could be required to make fingerprint photography. In other cases, the fingerprint may be unclear or visible at all - it is known as latent fingerprints - and treatment is necessary to create a print that can be analyzed.

Dust with a powder that holds printing can be effective - otherwise chemical treatment is required. A number of different powders can be used to dust. These are usually black or white depending on the nature of the surface; For dark surfaces, white powder, such as chalk or oxide titanium, could be the best choice would be coal or graphite.

There are a number of chemical methods for the treatment of latent fingerprints. The long -term method is iodine. Iodine when heatedThe bottom of the sublimes, forming a steam that reacts with lipids in the fingerprint forming a heavily colored brown compound, so exposing it to steam printing often reveals it clearly.

Another chemical that is often used is ninhydrin; This is applied in the form of a liquid and reacts with the amino acids in the print when heated and creates a purple compound. The recently introduced technique is cyanoacrylate, which is also known as "super adhesive" because cyanoacrylates are the main ingredients of super adhesives. Cyanoacrylate steam, in contact with printing, forms sticky, whitish cloth. This can be further strengthened by dust or treatment with fluorescent chemicals.

Comparison of fingerprints corresponds to prints on patterns and Maran. The patterns describe the main structure of the ridges and the Aznov is divided into three main types of fingerprints: arches, loops and WHORLY, each of which can be divided into subcategories. Minoriae are small inconsistencies in the main pattern and fall into four categories: dots that are small, insulated fragments ridgeat; bifurcation, where the ridge is divided into two; islands where the ridge then breaks down and joins again; and the end of the ridge where the ridge ends. Fingerprints made at the crime scene can be compared to those of a particular suspect or a large database of fingerprints that are held electronically. In the latter case, the process of fingerprint comparison is largely automated using programs that use algorithms comparing printing.