Forensic Interviewing Techniques

Financial fraud investigations rarely end with the analysis alone. A Benford's Law deviation flags vendor payment irregularities. A duplicate-payment test identifies three vendors with the same address as a payroll employee. But the analysis produces hypotheses, not conclusions. The forensic accountant still needs to understand whether the pattern was intentional, whether it represents a control failure rather than deliberate fraud, and who had the knowledge and access to execute the scheme. Interviews are the primary tool for answering those questions.

Interviews in financial cases tend to fall into three categories. Background witness interviews gather context from people who are not suspected of wrongdoing: accounts-payable clerks, system administrators, and managers who can explain how a process is supposed to work. Corroborative interviews confirm or challenge what the documents show: you ask a vendor whether they actually performed the services the invoices describe. Target interviews engage with the person the evidence points toward. Each category requires a different calibration of approach, tone, and preparation.

In the late 1980s, a series of wrongful convictions in England and Wales, linked in part to false confessions obtained through oppressive police interrogation, led to a formal review of interview practice. The result, published in 1992 as national guidance for police officers, was the PEACE model, which reoriented the purpose of the interview from obtaining a confession to obtaining an accurate, complete account.

1. Preparation and Planning
   Review all available documents and prior accounts before the interview. Define the objectives clearly: what do you need this person to explain or confirm? Anticipate the likely explanations and think about how to probe them. Plan the physical setting, who will attend, and how the interview will be recorded.
2. Engage and Explain
   Introduce everyone present, explain the purpose and ground rules, address any questions about the process, and establish a baseline rapport. The subject should understand they are free to ask for a break, that the interview is being recorded if it is, and what will happen to the information provided.
3. Account
   Begin with a free-narrative invitation: tell me, in your own words, everything that happened. Listen without interrupting. Then probe with open, specific, and closed questions in that order, moving toward more directed questions only after the subject has given their unprompted account.
4. Closure
   Summarise what the subject has said, ask whether there is anything they want to add or correct, explain what will happen next, and thank them for their time. Leave the door open for follow-up contact if new questions arise.
5. Evaluate
   After the interview, assess what the account adds to or changes in the investigation. Identify gaps, inconsistencies, and new lines of inquiry. Update the interview log and investigation plan accordingly.

The PEACE model has been adopted or adapted by police services in Australia, New Zealand, Scandinavia, Canada, and many other jurisdictions. Its influence on corporate investigation practice is also substantial: it provides a defensible structure that organizations can point to when challenged on how interviews were conducted.

The cognitive interview, developed by psychologists Ron Fisher and Edward Geiselman in the early 1980s and refined through subsequent empirical testing, is designed to maximise the accuracy and completeness of witness memory. Its core techniques derive from the encoding-specificity principle: memory retrieval is most effective when retrieval conditions approximate the conditions under which the memory was formed.

• Context reinstatement: Ask the witness to mentally return to the setting of the event before recounting it. Physical details (temperature, smells, sounds) help reinstate the context in which the memory was formed.
• Report everything: Encourage the witness to report every detail, even if it seems trivial. Witnesses often self-censor details they think are irrelevant. Seemingly minor details can become significant when combined with other evidence.
• Change order: Ask the witness to describe events from the end backward to the beginning, or from a mid-point. This disrupts the narrative heuristics that can suppress detail and force genuine memory retrieval.
• Change perspective: Ask the witness to describe what another person present would have seen. This exercises different aspects of the memory trace and can surface details not recalled from the original perspective.

In financial investigations, a pure cognitive interview is most useful for background witnesses who have genuine information to share but may not have organised or prioritised it. An accounts-payable manager being asked to recall the process for approving an unusual vendor will benefit from context reinstatement and the report-everything instruction. The technique is less relevant for target interviews, where the primary challenge is eliciting accurate disclosure from someone with a motive to withhold.

The Reid technique, developed jointly by Fred Inbau and John Reid and first described in their 1962 book Criminal Interrogation and Confessions (with Inbau listed as lead author), became the dominant framework for police interrogation in North America for several decades.

The first phase of Reid is a behavior analysis interview (BAI), a structured diagnostic interview that claims to identify deception from verbal responses and non-verbal behaviour. The problem is that controlled studies consistently show that trained Reid practitioners do not detect deception significantly better than chance. The technique was nonetheless widely used, and its association with documented false confessions, including several high-profile wrongful conviction cases later resolved by DNA evidence, has driven a substantial shift in practice in criminal justice settings.

Financial investigation interviews share a common structural logic across frameworks. The opening establishes the ground rules and explains the process. The middle section uses funnel questioning, starting wide and open, then narrowing progressively as specific anomalies are introduced. The close captures the subject's explanation of particular documents or transactions and gives them an opportunity to correct the record.

Introducing documentary exhibits is a skill in itself. Show the document without comment and ask the subject to read it, then ask open questions about what they recall about it. Providing the interpretation before the subject has given their unprompted reaction contaminates the account. If the subject's explanation of a document is inconsistent with other evidence, the inconsistency should be probed in the same session rather than saved for a follow-up interview if possible, because subjects may alter their account after learning that documents have been reviewed.

An interview that is not contemporaneously and accurately recorded has limited evidential value. Memory degrades and is susceptible to post-event contamination. In civil and regulatory proceedings, the interview record itself may become a key exhibit; in criminal matters, the way the interview was conducted and documented can determine whether a statement is admissible.

• Audio and video recording: Provides the most accurate record and is increasingly standard practice. Consent requirements vary: some jurisdictions require only one-party consent, others require all parties to consent. Check local law and the organisation's employment agreements before recording.
• Contemporaneous notes: If recording is not available or appropriate, a detailed note should be written immediately after the interview, while memory is fresh. Note the date, time, location, persons present, and the substance of what was said in as close to verbatim form as possible.
• Memorandum of interview: A formal write-up of the substance of the interview, prepared after the session. It should distinguish between what the subject said verbatim and what is the interviewer's summary or paraphrase. Signed acknowledgment by the subject, where obtainable, strengthens the document.
• Witness-statement format: In matters that may proceed to court, a formal witness statement signed by the interviewee and compliant with local court rules (e.g., the statement of truth format in England and Wales) should be prepared for all material witnesses.

Private forensic accountants are not bound by the constitutional protections that regulate state actors (Miranda rights in the US, the Police and Criminal Evidence Act in the UK). They can question employees without caution. But that freedom has limits. Employment contracts may impose procedural requirements. Trade union recognition agreements may give employees the right to union representation in disciplinary investigations. In some jurisdictions, misrepresenting the purpose of an interview or the consequences of non-participation can give rise to civil claims. Ignorance of the applicable employment and privacy law framework is not a defence.