DNA identification may allow sparing the world from personality violent crimes. If the database would be created that would contain the genetic samples of every dweller of our planet, the offender would be found in couple of hours or even minutes after the crime "Any type of organism can be identified by examination of DNA sequences unique to that species". (Human Genome Project Information, 2006). Thus nowadays we can tell the genetic material of people and animal. The methodic that allow identifying an individual are not so precise at the moment, but the pace of development of the contemporary technologies allows us to foretell that in some years the size of the DNA fragments available for comparison will become bigger, which will allow the criminologists to commit precise individual identification.
Nevertheless, it is still that thousands of crimes have been solved using DNA identification during the past years. If there is enough of the genetic material the offender left on the crime scene, the criminologists can compare it with the sample taken from the suspect, and define whether the suspect was present on a crime scene.
Unfortunately, even DNA identification is often unable to provide an answer to the question whether the culprit is guilty of the crime. The fragments of genetic material, found on the crime scene, only mean that he/she was present there at some moment. Theoretically, the DNA fragments may exist on the crime scene or the evidence, for decades. Thus, unless the fragments were found on a victim's body, the criminologists cannot be sure that the suspect is guilty of a crime.
DNA, or deoxyribonucleic acid, is the main substance of which the sells in human body are made. DNA is the same in every cell of the individual's body, whether it's his/her saliva, blood, semen etc. Each person's DNA is different from every other, except for identical twins. (Micklos, Freyer, Crotty, 2003). Thus DNA is one of the unique factors that allow identifying a personality with almost 100% guarantee.
The percent of DNA which's different for different people is extremely small; it is one tenth of a percent. The other fragments are the same for all of the Homo sapiens, except for people who have some deviations in their genetic code. Usually those are people who suffer from serious illnesses, like the Down's syndrome etc.
DNA can be collected from lots of places on a crime scene. It can be found on the victim's body, or on some things that are present on the scene. For using DNA analysis a little spot of blood or saliva, or a single hair is enough. (What Every Law Enforcement Officer Should Know About DNA Evidence, 1999)
Even the smallest fragments of DNA can be used for to define the personality of the offender. Thus the person, who collects the DNA samples, has to be very careful for to prevent contamination of the DNA with water, dirt, mold, or other DNA samples. The contamination of the sample with other DNA can happen when someone touches the
evidence with bare hands, sneezes or coughs on them, touches some part of the face and than touches the evidence.
Nowadays it is mostly the PCR technique that is used for to identify the DNA sample. The thing is that when the samples are submitted for testing, the PCR process will copy all of the DNA samples present, as it cannot distinguish between the DNA found on the crime scene, and the DNA that contaminated it later.