The interview is the stage of a workplace investigation where the most significant mistakes are made, and where the consequences of those mistakes are most directly visible. A poorly prepared investigator asks questions that lead the witness rather than elicit their account. A poorly structured interview fails to put the allegation clearly to the subject. A poorly kept record produces a disputed account that neither side will agree on. Each of these failures is avoidable, and each is the kind of error that employment tribunals scrutinise with particular care.
My team and I are regularly called upon to assist with investigation interviews, ensuring compliance is maintained and no stone is left unturned. We have recently conducted investigation interviews for corporate clients across the UK, including London, Sheffield, Leeds, York, Coventry, Oxford, Preston and Southampton.
Fail to Prepare = Prepare to Fail
In my experience, the quality of an investigation’s interviews is the single most reliable predictor of the quality of its findings. An investigator who knows what they are trying to establish, has reviewed the relevant evidence before the interview, and understands how to ask questions that produce genuine accounts rather than confirmations of a predetermined view will consistently produce a more reliable and more defensible evidential record than one who approaches interviews as a formality.
This article sets out the practices that make investigation interviews effective: how to prepare, how to structure questions, how to manage the specific challenges of witness and subject interviews, and how to record and use what is said.
Preparing for Interviews
Preparation is not optional. An investigator who arrives at an interview without having reviewed the relevant evidence, without a clear sense of what the interview needs to establish, and without a considered approach to how the questioning will be structured, is operating at a significant disadvantage from the moment the interview begins.
Review the evidence first: all documentary and digital evidence relevant to the specific interview should be reviewed before the interview takes place. This means the emails, the financial records, the HR files, the system logs — whatever is available. An investigator who does not know what the documents show cannot test a witness’s account against them, cannot ask specific questions about specific discrepancies, and cannot identify when an account is inconsistent with the objective record.
Define what the interview needs to establish: each interview should have a clear purpose: what specific questions need to be answered, what parts of the evidential picture this witness can contribute to, and what the interview needs to produce for the investigation to progress. An interview that has no defined purpose tends to become a general conversation rather than an evidential enquiry.
Sequence before you schedule: the order in which witnesses are interviewed is a strategic decision, not a scheduling convenience. Interview those with the most indirect or peripheral knowledge first, those with direct involvement later, and the subject of the allegation last. This approach allows the evidential picture to be built progressively, reduces the risk that witnesses can align their accounts, and means that by the time the subject is interviewed, the investigator has the full context available to test their account against.
Prepare the interviewee: every witness should receive appropriate advance notice of the interview, written confirmation of its purpose, and — in the case of the subject — written notification of the allegation they will be asked to respond to. The notice period should be sufficient for the interviewee to prepare, arrange accompaniment if they wish, and consider any documents or witnesses they wish to rely upon.
Questioning Techniques
The single most important practical discipline in investigation interviews is the consistent use of open questions. Open questions invite the interviewee to give their account in their own words. Closed questions invite confirmation or denial. Leading questions suggest the answer the investigator is looking for. The difference is not merely stylistic — it determines the reliability and legal defensibility of what the interview produces.
Open questions: ‘what happened?’, ‘can you describe the meeting?’, ‘how did the conversation end?’ — these invite narrative accounts that are informative precisely because they have not been shaped by the investigator’s assumptions. An open account that is internally consistent, specific, and supported by the documentary record is the strongest form of witness evidence available.
Probing questions: once the interviewee has given their initial account, probing questions allow the investigator to explore specific aspects in more detail: ‘you mentioned the payment was approved by the finance manager — can you tell me more about how that approval worked?’ These are still open but more targeted, and they should follow the initial account rather than interrupt it.
Clarifying questions: where an account is ambiguous, incomplete, or inconsistent with the documentary record, clarifying questions address those issues directly: ‘you said the meeting took place on Tuesday, but the email chain suggests it was Thursday — can you help me understand that?’ These are specific but not leading — they identify a discrepancy and invite the interviewee to address it rather than suggesting an answer.
Questions to avoid: leading questions (‘you were aware of the policy, weren’t you?’), double questions (‘did you approve the invoice and did you notify your manager?’), and evaluative questions that invite the interviewee to assess someone else’s conduct (‘do you think what they did was wrong?’) should all be avoided. Each produces unreliable evidence and creates grounds for challenge.
Witness Interviews
Witness interviews in workplace investigations serve a specific purpose: to gather accounts from individuals who have direct or indirect knowledge of the conduct under investigation, in a form that can be reliably used in the analysis of findings. Managing them effectively requires an understanding of the specific challenges they present.
Witnesses often have partial or peripheral knowledge, and the investigation needs to understand the scope of what each witness actually saw, heard, or experienced rather than treating their accounts as more comprehensive than they are. Asking a witness ‘what do you know about the situation?’ invites a wide-ranging account that may include hearsay, opinion, and inference alongside direct observation. Asking ‘on the 14th of March, were you present at the team meeting?’ focuses the interview on what the witness can speak to directly.
Witnesses should be reminded before the interview of the confidentiality requirements of the investigation — that they should not discuss it with colleagues — and their response to that reminder should be noted. Where a witness has already spoken to colleagues or to one of the parties before being interviewed, that should be recorded and its potential effect on their account noted in the analysis.
Where a witness raises a matter outside the scope of the investigation that appears significant — a separate concern, a prior incident, or conduct involving a different individual — that matter should be noted but not pursued in the current interview. The investigation’s scope is defined by its terms of reference, and conducting an unbounded enquiry through witness interviews creates risks for all parties.
Subject Interviews
The interview with the subject of the investigation — the person whose conduct is under examination — is the most legally significant interview in the process and the one most frequently mishandled. The requirements are specific and need to be met explicitly, not approximately.
Before the interview, the subject must receive written notification of the nature of the allegation against them, in sufficient detail to prepare a response. They must be informed of their right to be accompanied at a formal investigative interview under the Employment Relations Act 1999. They should be given a reasonable opportunity to review any documents that will be put to them in the interview, where doing so does not compromise the integrity of the investigation.
In the interview, the allegation should be put clearly and specifically at the outset: not ‘we have some concerns about your expense claims’ but ‘between January and March this year, you submitted expense claims totalling £4,200 that are alleged to be fraudulent. I want to ask you about those claims specifically.’ The subject’s response should be allowed to develop in full before the investigator probes specific inconsistencies or asks about specific documents.
Where the subject provides an account that is inconsistent with the documentary record, that inconsistency should be put to them directly and their response recorded. Where they decline to answer specific questions, that declination should be noted. Where they provide information that changes the direction of the investigation — identifying a witness, presenting a document, or raising a consideration the investigation had not previously addressed — that information should be assessed on its merits and followed up appropriately.
The subject’s interview is not the place for the investigator to express a view on credibility, to indicate what finding they are inclined toward, or to put pressure on the subject to change their account. The investigator’s role is to listen, to probe, and to record. The analysis belongs in the report.
Recording Information
The interview record is one of the most significant documents in any workplace investigation. It is the primary evidence of what was said, and it will be referred to in the analysis of findings, in the disciplinary process, and in any subsequent legal proceedings. Its accuracy and completeness matter.
Verbatim or near-verbatim: the record should capture what the interviewee said, in their own words, rather than the investigator’s summary or interpretation of their account. Where the investigator’s summary is used, it should be clearly identified as such and the interviewee should have the opportunity to correct it.
Share for review: every interview record should be shared with the interviewee as soon as possible after the interview and they should be given a reasonable opportunity to review and correct it. Where they dispute a part of the record, the dispute should be noted. Where they confirm it, that confirmation should be recorded. Where they decline to engage, that should be noted.
Record everything: the record should include anything that was said, including accounts that were ambiguous, inconsistent, or difficult to interpret. Editing out the inconvenient parts of an interview record — because they complicate the analysis or favour a less preferred interpretation — is an analytical dishonesty and a legal risk.
Contemporaneous notes: where a verbatim record is not being taken, notes should be made during or immediately after the interview and the record produced as soon as possible. Notes made days or weeks after the interview, or reconstructed from memory, are of significantly lower evidential value and are more likely to be challenged.
Common Interview Mistakes
Asking leading questions: the most common and most consequential interview error. A witness who has confirmed a leading question has provided less evidence than one who has answered an open question. Evidence obtained through leading questions is unreliable and susceptible to challenge.
Interviewing the subject before reviewing the evidence: an investigator who has not reviewed the documentary record cannot test the subject’s account against it. The subject has a significant advantage in an interview conducted by someone who does not know what the documents show.
Failing to put the allegation clearly at the outset: a subject interview that begins without a clear and specific statement of the allegation does not give the subject a genuine opportunity to respond. It may also produce an account that is incomplete because the subject did not understand what they were being asked to address.
Allowing the witness to depart from the relevant scope: witnesses who provide extended accounts of matters outside the investigation’s scope create two problems: they produce material that complicates the analysis, and they may raise expectations that the investigation will address matters it was never asked to examine. Keeping witness interviews within the defined scope is the investigator’s responsibility.
Failing to record the interview contemporaneously: an interview record produced days after the interview, without contemporaneous notes, is a weaker and more challengeable document than one produced promptly. In any contested proceeding, the gap between the interview and the record will be highlighted.
Accepting an account without probing inconsistencies: an investigation that accepts every account at face value, without identifying and following up inconsistencies with the documentary record or with other witness accounts, has not conducted a thorough investigation. Probing inconsistencies is not an act of hostility toward the witness — it is the mechanism by which the investigation tests the reliability of what it has been told.
Post written by lead investigator – Jamie Styles.
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