 After 48 hours when the sample has reached room temperature it is centrifuged, which allows the organic matter to completely oxidize, and the pellet is extracted, mixed with distilled water, and examined on a slide.The ratios of the different specimen of diatoms are counted, which allows scientists to match the area where the victim entered the water.Materials taken from victims, suspects, or the crime scene can also be tested to match locations of where the samples derived.