Clave Para Sound Blater X-fi Mb

An attacker on the scene" II "

Let us therefore look a bit more in the previous article . It turns out that the famous principle of exchange " Quiscunque tactus vestigia Legat (all contact leaves a trace) is a valid fact which strengthens our research activity, but also, as we said, you can throw to fret when we ourselves or our collaborators who through ignorance, accidental or recklessly pollute nature.

Inevitably, those who commit crimes and not acting physically do about things and events occur in mutual exchange that remains.

This can occur between people, between people and objects and between objects. So we are talking about primary transfer , which is what happens between the aggressor and the scene (and vice versa), the aggressor and the victim (and vice versa), or the investigator (or other participants) and the scene or victim (and vice versa). But there would be a secondary transfer , which would be from a previous contact. What happens, then the existence of the latter can multiply the workload, but also the value of trace evidence, so that sometimes enable us to relate several scenes together, that is, those who have been involved in the action criminal and those that belong to the author's environment. Of course, without you look carefully at what has been said-and, more specifically, the primary transfer occurs between the researcher and the scene or the victim-back, something that distorts the transfer process and simply resulting in contamination .

The techniques currently used in laboratories, are so developed that allow a differential analysis and comparison to almost everything, with the consequent cost, of course. So, another reason for its wise use, go necessarily prevent our irregular activity, slow down the process when not collapsed. At this point, which we reached theorizing practical reflection of the previous article, only remains to put a stop to this outrage and do a series of recommendations to avoid the fiasco of the inspection.

For example, we said that whoever arrives first at the scene, his performance generic passed to protect the scene. This implies, in addition to visually check the reality of the criminal and arrest the perpetrator if he were still there; neutralize imminent risks and dangers; auxiliary wounded taking notes of witnesses and other service personnel who are there, drive curious ... .- also use from the start and at least latex gloves, especially in the cases to be handled exceptionally signs and effects of crime, in which case it shall be always less common places such as corners, edges, parts interiors, etc.

All indications are important, but perhaps, for a decade, DNA technology has acquired a special role when we need to collect and analyze biological evidence of criminal interest. A priori, we can extract genetic material from any biological evidence (blood, hair, semen, epithelial debris, saliva ... etc..) And even with the new techniques of gene amplification (PCR, or chain reaction of polymerase) from minute quantities of genetic material-pg-o this highly degraded samples, we have obtained very precise information about the identity of the person from which the clue.

With what, in short, the result DNA testing will have much to do with the quality of training, but more for how to make the collection and shipment to the laboratory. The admissibility of evidence by the courts, with sufficient guarantee of authenticity and integrity, necessarily involves a quality filter is called chain of custody .

As noted, the collection of evidence generally requires proper protection using gloves, but also mask, hat, pants, and disposable overalls. And, since biological evidence prominently in the criminal investigation, we say to older, for their protection, it is important to dry traces at room temperature (not to act microorganisms) and without exposing to sunlight (ultraviolet radiation that does not degrade the DNA.) Once

protected
the next step is the collection, which, depending on the case, it is necessary the use of clean containers, porous and independent, as would be paper bags or cardboard boxes. These packages provide the sweat and avoid degradation itself would occur if the container was plastic.

If the sign is a biological liquid stain, we can collect a sample of it with a swab, allow it to dry at room temperature and placed in a container paper or cardboard. In the same evidence but with the stain dry, we apply another swab, but this time wetting in saline, then dried and placed in a container of paper or cardboard as the previous case.

may be obvious, but it is worth remembering that one should not speak or sneeze into the samples, to be used, as far as possible, disposable, single use and, remain valid for the selection, handling and collection of all the evidence that we can find, they must collect minimally logical and verifiable, which normally do not fit in that environment and not repetitive. The final step to endorse the chain of custody, would be singled out with reference labeling and unique addition to the exact place of origin.

To end and since we're talking about biological evidence, whenever possible, take a buccal swab as shown undoubted reference.

Author: Roberto Fernández Carro, QDC 11 .