Answer Framework:
Phase I (Laboratory Investigation): Verify that the analyst followed standard test methods, instrument parameters were within calibration, solutions/standards were valid, and chromatograms/system suitability met criteria.
Phase II (Manufacturing / Root-Cause Investigation): If Phase I identifies no clear laboratory error, open a Phase II cross-functional investigation. Examine the batch manufacturing record (BMR), equipment logs, process alarms, material lots, environmental controls, and operator interventions.
Hypothesis Testing & Re-testing: Re-testing must follow an approved protocol with pre-defined criteria; re-testing into compliance without justified hypothesis testing is strictly avoided.
Disposition & CAPA: Make the final batch release decision based on totality of evidence, risk to patient safety, and regulatory impact, followed by robust CAPA to prevent recurrence.