Answer:
Request a copy of the company's code of ethics.
Step-by-step explanation:
Interviewing the managers and employees who made the mistake wouldn't be constructive as much as it is needed for a first step in mitigating such a big future risk (and correcting what has been done already). Instead, the auditors should inspect the existing code of ethics and see in what way has it been breached. The worse case would be if the rules that could be potentially breached are non-existent. Then, a full remake of the code of ethics would be the first step in rebuilding the company's ethos.