Upon receipt of the case, exhibits and known samples are handled according to a standardized evidence control system to maintain sample integrity:

1. Samples are inspected and properly documented upon receipt.

2. Any inconsistency between the sample and accompanying documentation or other inconsistency is documented and the requestor is consulted for further instruction.

3. Samples are uniquely labeled for identification.

4. A comprehensive internal tracking document accompanies every sample.

5. Samples are stored securely to prevent any possible contamination or sample degradation.

The evidence control system is the first step in preventing potential sample contamination by ensuring the integrity of each sample. Additionally, specific precautions are taken to ensure quality control:

1. Exhibits and known samples are handled independently in physically separate and specified clean areas designated for that purpose.

2. Exhibits are handled and analyzed before known samples to provide a temporal separation between the two.

3. A unidirectional flow of sample and technical personnel is followed, with special attention to post-amplification products.