Both can be preserved until processing by simply placing a covering over both to prevent further contamination or destruction. The processing of the evidence in the crime scene requires the use of procedures that reduce the evidence destruction. All evidence should be first visually examined with the naked eye, then examined with the use a forensic light source, then processed in a non-destructive manner. Each of these steps must be carefully administered so as to not diminish the potential value of the evidence in the investigation. All physical evidence, once documented and processed at the scene, must be packaged properly.
Evidence packaging can be critical in the protection of the evidence.
If an item with a non-porous surface, such as a drinking glass, is packaged to be transported to the police agency or laboratory for further analysis, the glass must be packaged in a paper product so it can breathe and not cause mold. Packaging must also be done in a manner that preserves potential latent prints. For example, if the paper bag is too large, the glass could rub up against the walls of the paper bag and wipe off the prints. The packaging must be appropriate for the evidence. An essential element of the preservation of evidence is the sealing of the evidence bags or containers.