n population that is not very helpful but if you keep on finding more and more things eventually it is narrowed down to one specific person.Once the DNA is found how is it typed up?Only one-tenth of a single percent of DNA makes one person different from the next. Scientists can use these variable regions to create a DNA profile for a person, using samples from hair, blood, bone and other body tissues and products. Generally in criminal cases this involves getting samples from crime-scene evidence and a suspect giving off some DNA, and analyzing it for the presence of a set of specific DNA regions.Scientists find the markers in a DNA sample by designing small pieces of DNA called probes that will each seek out and tie to a complementary DNA sequence in the sample. A series of probes tied to a DNA sample creates a unique pattern for an individual. Forensic scientists compare these DNA profiles to the suspects sample to see if the suspects sample matches the evidence sample. If two samples are alike at four or five regions, most probably the suspect contributed his DNA to the crime-scene evidence, though there is a slim chance that someone else has the same DNA profile for a particular probe set. The question is how small of a chance must there be when convicting the guilty or the vindication of the innocent lies in the balance? The judges often let the jury decode based on this and other evidence involved in the case. Experts say that using DNA forensic technology is better then eyewitness accounts.Sources of DNA for testingBlood Once bloodstains are found an analysis can most probably be made. But it depends on the surface or substrate on which it is found. If the blood is found on glass, metal, hard plastics or lightweight cloth it is easy to extract the blood and analyze it. If found on other dense and heavily colored fibers a few additional steps are required. Soil and concrete are almost impossible substances and surfaces...
