Any difference in a proficiency test result proven to be the consequence of an analytical or interpretative discrepancy may prohibit the personnel who produced the discrepant result from further examination of case evidence until the cause of the discrepancy is identified and corrected. The quality assurance coordinator or designated personnel will determine the need to audit prior cases according to established laboratory policy.
Any discrepancy in a proficiency test determined to be the result of a systematic error may require a review of all relevant casework since the trace evidence section’s last successfully completed proficiency test using that equipment. Once the cause of the discrepancy has been identified and corrective action has been taken, examiners in the relevant area should be made aware of the appropriate corrective action.