Interviews are where internal investigations most visibly go wrong. Documents sit still; people do not. An interview conducted too early educates the interviewee instead of the investigator. A record kept carelessly turns a strong finding into a swearing contest. And an interview conducted unfairly can hand the company a fresh employment dispute on top of the problem it was trying to solve.
The good news: most interview failures are sequencing and preparation failures, and both are controllable.
Documents first, interviews second
The strongest reason to interview late is simple: you get one clean shot. The first interview with a key person is the one where their account is unrehearsed and their knowledge of what you know is lowest. Spend that shot before the document review is done and you cannot ask about the messages you have not yet seen — but the interviewee walks out knowing exactly what the investigation is interested in.
An interview after the review is a different instrument. The interviewer arrives with the chronology, knows where the record is clear and where it is silent, and can use questions for what only questions can do: explain intent, fill genuine gaps, test credibility. Now that structured review can cover the full document set quickly, "documents first" no longer costs months — the old excuse for interviewing blind is gone.
Sequence from the edges inward
Order matters almost as much as timing. The usual pattern is to work from the periphery toward the centre: first the people who can explain context and process — how approvals normally worked, who sat where — then the witnesses closer to the events, and last the subjects of the allegation, when the questioning can be anchored in documents rather than hypotheses.
Interviewing a subject first is occasionally justified, but it should be a decision, not an accident of who happened to be available. And every interview teaches the organisation that an investigation is running, so the sequence should assume that people talk to each other — because they do.
Records that hold up
Decide the form of the record before the first interview, and keep it consistent. The realistic options — the interviewer's structured notes, a detailed memorandum prepared promptly afterwards, a verbatim transcript, an audio recording — trade off accuracy, candour and effort differently, and recording brings its own consent and data-protection questions. What matters most is uniformity and honesty about what the record is: notes reflecting the interviewer's understanding are fine, as long as no one later presents them as a transcript.
Practical points that pay for themselves: a second person in the room taking notes, the record prepared while memory is fresh, and a considered decision on whether the interviewee reviews and confirms it. If the investigation is run under legal privilege, interview memoranda should be prepared by or for counsel within the mandate — how findings then circulate is its own discipline.
Fairness is not a courtesy — it is protection
Interviewees are entitled to know what they are walking into, within the limits the investigation can afford. That means saying plainly who the interviewers act for — the company, not the individual — why the conversation is happening, at least in outline, and what will happen to the record. Employees generally owe their employer cooperation under their duty of loyalty, but that duty has limits, and pressure that crosses into coercion poisons both the record and the employment relationship.
Fairness has a hard edge for subjects: before conclusions are drawn against a person, they should be confronted with the substance of the allegations and given a real opportunity to respond. Skipping that step is not just an ethical lapse — under Swiss employment law it can undermine the sanctions that follow, up to and including a dismissal that would otherwise have been defensible.
Do not create new problems while investigating old ones
The recurring self-inflicted wounds are avoidable: promising confidentiality or immunity the company cannot honour; making threats about consequences to force answers; sharing one interviewee's statements with another for leverage; letting interview content leak into corridor conversation, which can shade into reputational harm; and treating personal data collected in interviews as if data protection law paused for investigations — it does not. Cross-border interviews add another layer, because employment and data rules follow the employee, not the investigator.
Whether a particular interviewee should be offered counsel, warned formally, or interviewed at all is a judgment call that depends on the facts — on exposure, on the person's role, on what proceedings may follow. That judgment belongs to a lawyer who sees the whole board. If interviews are next on your investigation plan and the order or the ground rules feel uncertain, that is a good moment to talk — before the first invitation goes out.