Preparing for and Conducting Workplace Investigation Interviews

Why Interview Quality Determines Investigation Quality

The interview is the primary tool through which most workplace investigations gather their evidence. Documents and records establish the factual landscape. Interviews bring it to life, test it, and produce the witness accounts that the investigator must assess and weigh against each other. The quality of those accounts depends directly on the quality of the interviews that generated them.

Poor interview preparation produces unfocused, incomplete accounts that leave critical questions unanswered. Poor interview technique produces evidence that is contaminated by leading questions, shaped by the interviewer’s assumptions, or so superficial that it cannot bear the weight of the conclusions drawn from it. By contrast, well-prepared and well-conducted interviews produce clear, detailed and reliable accounts that give the investigator a genuinely sound evidential foundation.

This chapter covers both stages: preparing for interviews and conducting them. The two are inseparable. What happens in the preparation determines what is possible in the room.

This chapter is part of the Workplace and Corporate Investigations Knowledge Guide. If you need an independent investigator see my independent workplace investigator page.

Choosing Which Witnesses to Interview

The starting point is identifying who needs to be interviewed. This is not simply a matter of interviewing everyone who has been mentioned or who has expressed a view. It requires judgment about which witnesses are likely to have direct, relevant knowledge of the matters under investigation and which will add little that cannot be established through other means.

Essential witnesses include the complainant, the subject of the allegations, and any witnesses who directly observed the events or conduct in question. Beyond these, the investigator must assess which additional witnesses have genuine first-hand knowledge that bears on the central allegations, as opposed to witnesses who can only offer opinions, second-hand accounts or background information that is unlikely to affect the findings.

Interviewing too many witnesses creates unnecessary burden on individuals who may find the process stressful, generates large volumes of evidence that must be assessed and documented, and risks introducing peripheral material that distracts from the central issues. Interviewing too few may mean that significant evidence is not gathered. The right number depends on the specific case, not on a general formula.

Choosing the Order of Interviews

The order in which witnesses are interviewed matters more than is often appreciated. The general principle is that witnesses with the most direct knowledge of specific events should be interviewed before witnesses with only partial knowledge, so that the investigator builds a clear picture of the central events before exploring their context. The subject of the allegation is generally interviewed after the complainant and the principal witnesses, so that the investigator can put the evidence gathered from those interviews to the subject and give them a fair opportunity to respond to it.

Interviewing the subject first, before the evidence has been gathered, means that the investigator cannot put the full picture to them and the subject cannot respond to specific evidence they have not yet seen. This is not only procedurally problematic but also practically inefficient, because the interview must often be repeated once the evidence has been gathered.

Where witnesses may be influenced by each other’s accounts, steps should be taken to conduct interviews before witnesses have had the opportunity to discuss the matter between themselves. This is particularly important in workplaces where the relevant individuals work closely together and communication is frequent.

Deciding Between Interviews and Written Questions

In most cases, face-to-face or video interviews produce better evidence than written questions because they allow the investigator to probe, follow up, test inconsistencies and assess the witness’s account in real time. Written questions tend to produce polished, carefully considered answers that may say less about what the witness actually knows and more about what they have decided to disclose.

However, written questions may be appropriate in limited circumstances: where a witness is unable to participate in an interview due to illness or significant distance, where the questions are genuinely narrow and factual and do not require the kind of probing that only a live interview can provide, or where the witness has specific communication needs that make written questions more accessible than a live interview.

Where written questions are used, the investigator should be alert to the limitations of the responses and should not treat a carefully crafted written answer as equivalent to a tested interview account.

Preparing Interview Questions

Good interview preparation begins with a clear understanding of what the interview needs to establish. For each witness, the investigator should identify the specific questions that need to be answered and plan questions designed to elicit those answers without leading the witness toward a predetermined conclusion.

Interview questions in workplace investigations should be open rather than closed wherever possible. Open questions, beginning with words such as “tell me,” “describe,” “explain” or “what happened,” invite the witness to provide their own account in their own words. Closed questions, which invite yes or no answers, can be useful for clarifying specific points but should not drive the interview. Leading questions, which suggest the answer in the question itself, should be avoided entirely in the substantive questioning because they contaminate the account.

The preparation should also identify the documents and records that need to be discussed with each witness, the specific inconsistencies or conflicts with other evidence that need to be explored, and the allegations or evidence that need to be put to the subject so that they have a fair opportunity to respond.

Preparing the Interview Environment

The environment in which an interview takes place affects the quality of the evidence it produces. Witnesses who feel physically uncomfortable, exposed or under surveillance are less likely to speak openly and candidly. The interviewer should choose a private, quiet space where the conversation cannot be overheard, ensure that the witness knows they will not be interrupted, and consider whether the physical arrangement of the space, including seating positions and the presence of recording equipment, sends the right signals about the nature of the process.

Where interviews are conducted remotely via video conference, the same principles apply. The interviewer should ensure that both parties are in private spaces, that the technology is working reliably before the interview begins, and that the remote format does not inadvertently make the witness feel more exposed or scrutinised than they would in a face-to-face interview.

All interviews should be audio recorded and a verbatim transcript produced. Recording removes the risk of dispute about what was said, enables the investigator to focus on the interview rather than note-taking, and provides a reliable record that can be reviewed when assessing the evidence and writing the report. The witness should be informed of the recording at the outset and their consent obtained.

Starting the Interview: Engage and Explain

The opening of an interview sets the tone for everything that follows. Witnesses who understand the process, know what is expected of them and feel that they are being treated with respect are more likely to engage openly and provide reliable accounts.

At the outset the investigator should introduce themselves, explain their role and confirm their independence from all parties, explain the purpose of the interview and what it is intended to establish, confirm that the interview is being recorded and will be transcribed, explain the witness’s right to take breaks and to ask for questions to be repeated or clarified, explain that the witness should only speak to what they personally know or observed rather than what they have heard or assume, and explain confidentiality: what will and will not be shared, and with whom.

Building rapport at this stage does not mean being informal or chatty. It means creating a professional environment in which the witness feels that the process is being conducted with care and that their account will be taken seriously. Witnesses who feel heard and respected provide better evidence than those who feel interrogated or dismissed.

Interviewing Witnesses

The substantive interview should begin with an open invitation for the witness to provide their account in their own words, without interruption. This initial narrative is often the most valuable part of the interview because it reflects what the witness considers most important rather than being shaped by the investigator’s questions.

After the initial narrative, the investigator should systematically explore the key areas identified in the preparation, using open questions to develop the account and probing questions to test it. Probing includes following up on vague or incomplete answers, exploring inconsistencies within the account, asking the witness to clarify the basis for their assertions, and examining any aspects of the account that seem implausible given the other evidence.

Documents and records relevant to the witness’s account should be put to the witness during the interview so that they can comment on them. Where a document appears to contradict the witness’s account, they should be given a fair opportunity to explain the inconsistency before any conclusion is drawn from it.

The investigator should avoid arguing with the witness, expressing opinions about the credibility of their account during the interview, or allowing the interview to become adversarial. The goal is to gather the most complete and reliable account possible, not to win an argument.

Interviewing the Subject

Interviewing the subject of an investigation requires a different approach from interviewing a witness, for both procedural and practical reasons.

Procedurally, the subject must be given a fair opportunity to respond to the allegations and to the evidence gathered from other witnesses. This means that the subject’s interview should normally take place after the principal witnesses have been interviewed, so that the specific evidence can be put to them. The allegations must be put clearly and in sufficient detail that the subject understands what they are being asked to account for. They must be given the opportunity to respond to each allegation and to comment on the key evidence that bears on it.

Practically, the subject’s interview is likely to be more challenging than witness interviews because the subject has a significant personal stake in the outcome. They may be defensive, evasive, hostile or highly controlled in their responses. The investigator must maintain professional composure throughout, probe carefully without becoming adversarial, and ensure that the record accurately reflects both what was asked and what was answered, including where the subject declined to answer or gave an answer that was unresponsive to the question.

The subject has the right to be accompanied by a trade union representative or a work colleague at any disciplinary or grievance interview. Their right to be accompanied should be confirmed in advance, and any request for accompaniment should be accommodated where reasonably practicable.

Trauma-Informed Interviewing

Some witnesses in workplace investigations have experienced events that are genuinely traumatic. This is particularly likely in investigations involving sexual misconduct, serious bullying, safeguarding concerns or other conduct that has caused significant personal harm. Trauma-informed interviewing recognises that witnesses who have experienced trauma may recall events differently, present inconsistently, display heightened emotion or apparent detachment, or find the interview process itself distressing in ways that affect the quality of their account.

These responses are not indicators of unreliability. They are common reactions to trauma that must be understood and accommodated rather than used to undermine the witness’s credibility. A trauma-informed approach involves explaining the process clearly before the interview begins, pacing the interview carefully and allowing breaks where needed, avoiding unnecessary repetition of distressing details, using non-judgmental language throughout, and being prepared to adapt the interview format where the witness’s needs require it.

Properly applied, trauma-informed practice improves the quality of the evidence gathered because it creates conditions in which the witness can provide their best account rather than being further distressed by the process. For detailed guidance on vulnerable and neurodivergent witnesses see the chapter on considerations for particular types of investigation.

Using AI Tools to Support Interviewing

AI tools are increasingly used to support the interviewing process in workplace investigations, primarily in two ways: generating transcripts from audio recordings, and assisting with interview planning and question preparation. Used appropriately, these tools can significantly reduce the administrative burden of the interview process and improve the accuracy of the record.

However, AI tools must be used with clear understanding of their limitations and risks. AI-generated transcripts require careful review and correction before they can be relied on as an accurate record. AI-assisted interview planning can help structure the preparation but must not replace the investigator’s own judgment about what the specific case requires. AI must not be used to assess witness credibility, determine the weight of evidence or reach investigative conclusions. For a detailed treatment of AI in workplace investigations see the chapter on AI in modern workplace investigations.

Published Resources

My book The Workplace and Corporate Investigator’s Handbook covers both chapters of this topic in full, including a comprehensive treatment of open, closed, probing and clarifying questioning techniques, the specific approach to interviewing complainants, witnesses and subjects at different stages of the investigation, building rapport while maintaining independence, the use of AI in interviewing, and the full Meadowbrook Care Home worked example showing how these principles apply in a complex real-world investigation.

See all books.

Frequently Asked Questions

Should all interviews be recorded?

Yes, wherever possible. Audio recording removes the risk of dispute about what was said, enables the investigator to focus on the interview rather than note-taking, and produces a reliable verbatim record that can be reviewed when assessing evidence and writing the report. The witness should be informed of the recording at the outset and their consent obtained. A written transcript should be produced from the recording and provided to the witness for review.

Does a subject have the right to be accompanied at an interview?

Yes. Under section 10 of the Employment Relations Act 1999, workers have the right to be accompanied by a trade union representative or a work colleague at any disciplinary or grievance hearing or interview. This right should be confirmed in advance of the interview and any request for accompaniment accommodated where reasonably practicable.

Can a witness refuse to be interviewed?

A witness who is an employee cannot be compelled to participate in an investigation interview as a matter of strict law, but refusal to cooperate with a reasonable investigation instruction may itself constitute a disciplinary matter. The investigator should explain the purpose and importance of the interview clearly, address any concerns the witness has about the process, and document any refusal and the reasons given. The investigation can proceed without the witness’s account, but the investigator must note that the evidence is incomplete and consider what weight can be given to findings in that circumstance.

Should an interview be stopped if a witness becomes distressed?

Yes, where the distress is significant. The investigator should offer a break, check whether the witness wants to continue, and consider whether adaptations to the interview format would help. Where a witness is unable to continue the interview due to distress, it can be reconvened at a later date. Pressing on with an interview when a witness is significantly distressed produces unreliable evidence and may cause real harm to the witness.

What should an investigator do if new information emerges during an interview?

New information that is relevant to the investigation should be explored in the interview where possible. Where it raises issues that go beyond the current scope of the investigation, the investigator should note it and consider whether the terms of reference need to be expanded before proceeding, or whether the matter should be referred separately. New information that amounts to a new allegation against the subject must be put to them fairly before any finding is made on it.

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Important disclaimer: This page is provided for general information and educational purposes only and does not constitute legal advice. The content may not be legally accurate for your specific situation. You must not rely on anything on this page in respect of your legal rights or obligations. Always seek independent legal advice before taking or refraining from taking any action. The author accepts no responsibility for any decisions made or outcomes arising from use of this material. If you would like specific advice, contact me here.

Preparing for and conducting interviews