An investigation is a fact-finding exercise to collect all the relevant information on a matter. A properly conducted investigation can enable an employer to fully consider the matter and then make an informed decision on it.

Making a decision without completing a reasonable investigation can make any subsequent decisions or actions unfair, and leave an employer vulnerable to legal action.

The role of an investigator

The role of an investigator is to be fair and objective so that they can establish the essential facts of the matter and reach a conclusion on what did or did not happen. An investigator should do this by looking for evidence that supports the allegation and evidence that contradicts it.

In potential disciplinary matters, it is not an investigator’s role to prove the guilt of any party but to investigate if there is a case to answer.

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STEP 1: Organisational preparation

  • Decide if an investigation is necessary
  • Establish terms of reference – the rules that the investigation will follow, including precisely what needs to be investigated
  • Choose an appropriate investigator

STEP 2: An investigator’s preparation

  • Draft an investigation plan
  • Identify who might need to be called to an investigation meeting
  • Identify what evidence might need to be gathered – and how to get it
  • Contact parties involved in the matter

STEP 3: Handling an investigation meeting

  • Establish who can accompany employees at the meeting
  • Plan what questions need to be asked
  • Interview the parties involved and any relevant witnesses
  • Handle reluctant witnesses or refusals to meet appropriately

STEP 4: Gathering evidence

  • Arrange and agree witness statements
  • Collect any relevant written records and documents e.g. timesheets
  • Collect any relevant and appropriate physical evidence e.g. CCTV

STEP 5: Writing an investigation report

  • Plan the structure of the report – remember there is a free Acas template available to use or adapt
  • Report what is likely to have happened – the balance of probabilities
  • Make a recommendation where requested

STEP 6: After an investigation is completed

  • Submit the report and conclude the investigator role
  • Retain the report for an appropriate period of time
  • Ensure any recommendations unrelated to the matter are considered

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Choosing an investigator

Who should be the investigator will often depend on the seriousness and/or complexity of the matter:

  • In the majority of cases, where the matter to be investigated appears to be clear and the facts are not in dispute, the role of investigator may be carried out by an appropriate line manager or someone from HR for instance
  • If the evidence to be investigated is more serious or complex (such as potential gross misconduct, discrimination or bullying) then, where possible, appointing someone more senior or experienced may be beneficial. However, an employer should be careful to ensure that there are still appropriate members of staff available if a disciplinary hearing (and appeal hearing) may be necessary
  • In exceptional circumstances, it may be appropriate to appoint someone who is as detached from the matter as is practical, such as an external consultant. However, this needs to be carefully considered and any decision should balance the needs for fairness against a cost- effective and efficient investigation

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Possible temporary measures

Many investigations may be conducted without removing an employee from their typical working environment. On occasions, an employer may need to consider taking a temporary measure while an investigation is conducted.

Temporary transfer

Sometimes, rather than the more extreme measure of suspension, it may be more practical and productive to transfer an employee to a different area of work on a temporary basis. If tensions between certain employees within the organisation are high then a temporary transfer can stop them having to work together while the investigation is carried out.

In practical terms a temporary transfer will not always be possible. Where it is used, an employer should be reasonable and treat an employee fairly. An employer should only transfer an employee to a job of similar status in the organisation.


In certain situations, an employer may decide that suspension with pay is necessary while the investigation is carried out. This may include where:

  • working relationships have broken down
  • the employee could tamper with evidence
  • there is a risk to an employee’s health or safety
  • property or the business of an employee or the organisation may be damaged

Suspension with pay should only be used after careful consideration, as a last resort and should be reviewed to ensure it is not unnecessarily drawn out. It should be made clear that the suspension is temporary, not an assumption of guilt and not a disciplinary sanction.

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Identify possible parties relevant to the investigation

When individuals might be able to provide information relevant to the investigation, an investigator may interview them and/or ask them to provide a witness statement.

Where a large number of people witnessed the same incident, it will usually not be necessary to interview everybody. An investigator should interview some of the witnesses. If their accounts are consistent then an investigator may not need to interview other witnesses unless there are good reasons to believe they might have further information on the matter.

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Inviting relevant parties to an investigation meeting

An investigator should give any employee that they intend to interview advance written notice of their investigation meeting.

Conducting workplace investigations

The invitation should include…

  • the date, time and place of the meeting
  • the name of the investigator and what their role is
  • the reason for the meeting
  • an explanation that the meeting is only to establish the facts of the matter and is not a disciplinary meeting
  • a request to keep the reason for the meeting, and any discussions that take place, confidential
  • whether there is a right to be accompanied to the meeting that it may be a disciplinary issue if they unreasonably refuse or fail to attend the investigation meeting

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Can an interviewee be accompanied?

In many cases it will benefit an investigation (and may be work place policy) to allow an interviewee to be accompanied by a workplace colleague or trade union representative. An employer might even consider allowing a personal friend or family member to accompany an interviewee if this is reasonable in the circumstances.

While there is no statutory right to be accompanied at an investigation meeting, an employee may still have a contractual right if not being accompanied would leave them unfairly disadvantaged.

Allowing an interviewee to be accompanied can help for the following reasons:

  • english may not be their first language and a companion may be in a position to help facilitate the discussion
  • having someone there with them can make an interviewee feel more comfortable and more willing to talk openly about the matter
  • a companion may be able to help an investigator manage the process more effectively by explaining steps being taken to an interviewee
  • it can increase the confidence staff have in a credible process, and therefore may reduce the potential for appeal against any decision that follows

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The Interview Process

Before the meeting takes place an investigator should

  • establish how the interviewee may be able to help with the investigation and plan initial questions accordingly
  • book an appropriate time and place for the meeting
  • write to the employee inviting them to the meeting and detail any rights of accompaniment

At the start of the meeting an investigator should explain

  • who is present and why
  • the role of the investigator
  • the purpose of the meeting
  • the need for confidentiality during theinvestigation
  • that the interviewee’s witness statement may beused in an investigation report
  • who will see the interviewee’s witness statement

During the meeting an investigator should

  • ask questions to gather the facts of the matter
  • probe the interviewee without it being in anadversarial manner
  • record responses and any refusal to respond
  • seek evidence that may substantiate theinformation provided

At the end of the meeting an investigator should

  • check if there is anything else the interviewee thinks is important before ending the interview
  • ask if there are other witnesses that they thinkshould be interviewed and why
  • explain that they may need to be interviewed again
  • explain that the interviewee will be providedshortly with a copy of their witness statement for them to check and confirm that it is accurate

After the meeting an investigator should

  • provide the interviewee with a copy of their statement and seek agreement that it is accurate
  • consider what the important facts from the meeting were and whether evidence already collected supports or contradicts these
  • consider whether the meeting suggested any further evidence needs to be collected or interviews arranged