Investigating incidents - tips on effective witness interviews

Incident investigations are triggered when something has gone wrong – maybe a quality failure, a safety incident, or an environmental spill, for example.

Most incident investigations are carried out by someone within the organisation, often from the safety, quality, or operations team, depending on the nature of the incident. When things go seriously wrong – an incident with a significant financial cost or loss of life for example – a professional investigator is likely to be called in.

Investigators work backwards from the incident, potentially looking at days, weeks, months, or sometimes even years of contributing events, to establish what the key issues and failures were, and ultimately, the root causes of those key issues.

Much like an audit, investigators might review documents, inspect equipment, and speak to those involved, but the mindset of investigating is different. With investigations, we talk more about interviews, and there’s a greater emphasis on techniques like the PEACE model, gathering witness accounts, and building a timeline of events.

The importance of interviews

Interviews are a key part of understanding what really happened in an incident, and why.

Talking to witnesses – individuals who were involved or who have relevant knowledge of the situation – can provide valuable insights that support a fair, accurate, and robust investigation.

It’s essential to plan what will be covered in a witness interview, and how to approach conversations in a way that builds trust and encourages openness, so investigators can gather the information they really need.

Here are some tips for investigators to carry out for successful witness interviews.

Questioning

• Think the question through before you ask it
• Initially use open questions to get more detail, rather than closed questions that will only elicit yes/no answers
• Ask complete questions, one at a time. Multiple questions are very confusing
• Refrain from jumping in when the question has been answered. Silence often leads to further information
• Use a calm, respectful tone that can build trust and encourages openness
• Don’t suggest answers or make assumptions

Listening

• Put distractions aside. Show you’re focused on them, not your next question
• Let them speak freely. Interrupting can shut down useful detail
• Nod, maintain appropriate eye contact, and avoid closed body language
• Don’t rush to fill gaps. Pauses and brief silences often lead to additional meaningful insight
• Pay attention to how something is said, not just what is said
• Stay curious. Your job is to understand, not assume

Using the PEACE model

Interviewing well is a skill. It can be challenging to get the full picture while staying objective and fair. Following a clear structure like the PEACE model helps ensure consistency, builds confidence, and leads to better outcomes for everyone involved.

The model helps interviewers start with a plan, build rapport, gather accurate information, and ensure interviews are conducted fairly and professionally. Each stage plays a key role in supporting a thorough, balanced and value-adding interview.

P – Preparation and planning:

• Define the purpose and scope of the interview
• Gather background information and review available evidence
• Plan logistics (location, timing, roles, and any key questions)

E – Engage and explain:

• Build rapport and set a respectful tone
• Explain the interview’s purpose and process clearly
• Outline expectations and ground rules

A – Account and clarify:

• Use open questions to let them explain their version of events
• Probe for detail using follow-up and clarifying questions
• Avoid leading, suggestive or judgemental language

C – Confirm and close:

• Summarise key points and clarify anything unclear
• Offer the chance to add anything further
• Explain what happens next and thank them for their time

E – Evaluation:

• Reflect on the information gathered
• Assess accuracy, consistency, and any gaps
• Consider new questions for other witness interviews

Find out more

You can learn more about the PEACE model and how to conduct effective witness interviews on our Root Cause Analysis and Incident Investigation training courses.