The power of preparation: getting your investigation off to the best start

A version of the article was first published by People Management in August 2025.

Workplace investigations, whether relating to grievances, disciplinaries, whistleblowing or other sensitive issues, are often complex and can involve multiple employees and mountains of documents. Even investigations which may seem straightforward can take on a life of their own, draining time and resources. Taking steps to plan and scope the investigation before you start can make all the difference to ensuring the process that follows runs smoothly.

Step One: Is an investigation necessary?

When someone makes a complaint or an issue is raised, it can be tempting to launch straight into formal mode. However, the ACAS Code of Practice on Disciplinary and Grievance Procedures anticipates that “many potential…issues can be resolved informally”. Before you adopt the formal route, consider whether an informal resolution is appropriate and may be possible.

Start by examining the root of the issue – workplace problems, whether it’s a performance or conduct concern or a complaint about a colleague, often stem from a misunderstanding or from poor or miscommunication. Can the issue be nipped in the bud? If so an informal, facilitated discussion or similar between the individuals concerned may be all that is needed to successfully resolve the matter.

Step Two: Choosing the right investigator

Not all matters can be resolved informally, so if you do need to instigate your formal process, choosing the right investigator is key. The role of investigator can be challenging and time-consuming – the investigator will need to review evidence, ask probing questions of witnesses, make findings and, in some instances, recommendations as to next steps. They may also have to deal with highly sensitive issues such as sexual harassment allegations or whistleblowing complaints. Choose an investigator with the skills and, importantly, the time available to undertake the task.

When deciding who to appoint, it will also be important to consider seniority – ideally the investigator will be more senior than the person who has raised the complaint or is subject to the disciplinary investigation.

The investigator also needs to be independent to avoid the risk of actual or perceived bias. This means the investigator should be outside the management chain of those involved and, where possible, will not have any personal relationships with those involved, or any involvement in the issues under investigation.

Interestingly, it is becoming increasingly common for larger organisations, where investigations are more frequent, to have a specially trained team of managers to draw on as investigators.

Step Three: Scoping the issues to be investigated

Proper scoping of the issues under investigation at the outset will give the investigation structure and should assist the investigator to stay on track as the investigation progresses. Scoping the issues should also help keep the investigation focused and so should reduce the risk of delays or unnecessary diversions.

In scoping, keep in mind what the investigator is looking to achieve. For example, for a disciplinary issue they are seeking to establish if there is evidence to support a case to answer that should be escalated to a disciplinary manager, and for a grievance investigation, they will need to decide whether or not to uphold part or all of the grievance.

In all cases, it will be key for the investigator to be clear at the outset on what will (and will not) be investigated. The investigator should carefully consider each allegation to identify what it is they need to investigate, and the level of investigation required (noting that for grievances and disciplinaries, the ACAS Code requires employers to undertake “necessary” investigation, rather than exhaustive).

Grievances can be unwieldy and/or unclear. In these instances, it will often make sense for the investigator to speak to the employee at the outset to clarify and agree the issues to be investigated.

Step Four: Preparing an investigation plan

It can also be helpful to prepare a written plan for how the investigation will proceed. This can help avoid unnecessary delays.

The plan should set out each issue to be investigated, and in relation to each one, should identify; the relevant evidence to be gathered, the individuals to be interviewed, and any other actions that may be needed.

As part of the planning process, the investigator should consider a sensible order for conducting interviews, taking into account the chronology of events and also bearing in mind witness availability. The investigator should also factor time to consider the evidence and deliberate, as well as for drafting the investigation outcome or report. From there the investigator can anticipate the likely date that the investigation will conclude, as well as any interim milestones, factoring in any fixed timeframes contained in your policies.

HR can support the investigator with the planning and scoping exercise, and with collecting documentation and arranging meetings, but any substantive decisions should be taken by the investigator.

A well-planned investigation sets the tone for everything that follows. It helps to ensure that the process is efficient and that employee expectations are managed from the outset. This can mean the difference between a process that builds confidence and one that invites challenge.