Witness interviews: method before conviction

A witness statement is not a fact. It is an account of a fact, filtered through memory, position in the organisation, interests and fear. Interviewing witnesses means collecting that account with enough rigour for it to be tested against others, and with enough neutrality that it is not shaped by the person asking.

In an internal investigation the exercise is more delicate than it appears. Those interviewed are colleagues, sometimes subordinates, often anxious about their position. How the first question is framed largely determines the value of everything that follows.

Preparation is already investigation

A useful interview begins with document review: contracts, emails, access logs, the organisation chart, internal policies, exchanges with third parties. It continues with a provisional chronology, gaps acknowledged, and with at least two competing hypotheses. One hypothesis turns the interview into confirmation; two make it a search. That preparation takes time; it saves more on the day.

Sequencing matters. Starting with peripheral witnesses builds a factual base before approaching those most exposed, and allows precise questions rather than impressions. Each interview must be prepared individually: what this person could know, what they have already said, what would make them credible or not.

Conducting the interview

A few principles suffice, provided they hold without exception. Open with broad questions and let the person build their account before introducing documents. Do not suggest the expected answer. Do not accuse, threaten or promise. Restate the essential points and pin down dates, places and who was present.

Interviews are held separately, never in groups, and without opportunity for those involved to compare notes between sessions. Length must be enough to exhaust the subject, though a four-hour interview rarely yields more than a well-prepared two-hour one. Silence should be left open: information often surfaces in the gap. A recording, where lawful and accepted, does not replace the note: it completes it.

With an interpreter, the record must state the language of the interview and the mode of translation. With a vulnerable person, pace and phrasing change, a third party may need to be present, and restraint is required on matters unrelated to the subject.

Recording what was said

An interview is worth what its record is worth. The note must state date, place, duration, those present and in what capacity, the basis on which the person was asked to attend, the voluntary nature of the interview, and then report the statements faithfully.

• Separate facts directly observed from hearsay and from opinion.
• Quote verbatim the formulations whose wording matters, without polishing them.
• Note internal contradictions in the account, without commenting on them in the body of the note.
• Annex documents shown during the interview, with a note that they were produced.
• Date and version every note; never rewrite one after the fact without keeping the earlier version.

Where the witness agrees to sign, the written statement should be read through with them and signed without pressure. Where they decline, the interview note remains a dated working document, which is already substantial. Where two investigators attend, one leads the questioning and the other keeps the record; a single person doing both loses both. In all cases, the confidentiality of the exchange must be explained before it begins, and honoured afterwards.

The limits that are not crossed

A private investigator has no power of compulsion. They cannot detain a person, prevent them from leaving, oblige them to answer, record them covertly, present themselves as a representative of authority, or offer an advantage in exchange for a statement. Nor is an interview a negotiation: nothing should be offered, even indirectly, in return for cooperation. These limits are not formalities: crossing them renders the statement unusable and exposes both the investigator and the client.

A limit of judgement applies as well. Where criminal proceedings are open, an interview conducted without coordination can interfere with the investigation, expose the witness to pressure and weaken the whole. The question is not only what the law permits, but what the case can bear.

If you must establish contested facts before a decision — a sanction, a termination, an arbitration, a negotiation — an initial confidential consultation will define the interview plan, the points to be documented and the limits to observe. It commits you to nothing. These pages are editorial information and do not constitute legal advice.