How to Conduct a Fair Workplace Investigation, Step by Step

What is a workplace investigation, and when do you need one?

A workplace investigation is a fair, documented process for finding out what happened when a concern is raised: a grievance about a manager, an allegation of misconduct, a bullying or harassment complaint, or a report of wrongdoing. Its job is to establish facts. It is not a disciplinary hearing, and the investigator does not decide the outcome.

You need one whenever a decision about someone will rest on disputed facts, and whenever the matter is serious. A short records check may be enough for a simple, admitted lateness case. A complaint that a manager threatened someone for contacting HR needs a full investigation. Skipping the investigation leaves the decision-maker with no evidence to reason from, and leaves the outcome exposed at appeal.

Before anything else, triage the concern. Decide the route (informal, grievance, disciplinary, harassment or bullying, protected concern, capability) and check for escalation flags: possible crime, risk of harm, harassment linked to a protected characteristic, a link to an earlier complaint (possible retaliation), a senior person involved, health, possible dismissal or public interest. Any flag means involving senior HR or a legal adviser before you act.

Who should investigate?

Choose someone with no line or close personal relationship with anyone involved, who did not witness the events and has not formed or stated a view. They need time, training or support, and they must not be the person who will decide the outcome.

Good practice separates four roles: the commissioning manager who sets the terms of reference, the investigator who finds facts, the decision-maker who chairs any hearing, and an appeal manager. In a small organisation you may not have four suitable people; keep at least the investigator and decision-maker apart, and bring in someone from outside for the appeal if needed.

How do you write terms of reference?

Terms of reference are the investigator's brief, agreed before any interview. The most useful habit is to write each allegation as a specific, testable statement: who did what, when and where. 'On 19 February, the team leader told the complainant that if she went to HR again her hours would suffer' can be confirmed or contradicted. 'Inappropriate behaviour' cannot.

Then set the scope (what is in and out, and where out-of-scope matters will go), the standard of proof, the first evidence to gather and its retention risks, a timeline with update points, the output (findings per allegation and a recommendation on whether there is a case to answer, with wider recommendations kept separate) and confidentiality and support for everyone involved. If new allegations appear, amend the terms in writing and put them to the person they concern.

What evidence should you gather first?

Documents and data often settle cases that witness accounts cannot. Request anything that may be overwritten on the first day: CCTV, door-access and phone logs are often kept only for days or weeks. Then gather rotas, timesheets, training records, system logs, the policies and instructions in force at the time, and any notes made at the time, such as an email someone sent themselves that evening.

Keep a numbered evidence log (E1, E2 and so on) with the source, the date of the item and the date you obtained it. Prefer system exports to screenshots, which can be cropped. Work on copies and keep originals. A useful habit is to give each item a rough weight (strong if a reliable record can settle a point on its own, supporting if it needs something else with it, weak if it carries little or none), then revisit it when writing each finding. Collect only what you need and keep it under access control, because case evidence is personal data.

Look as hard for evidence that helps the person accused as for evidence against them. Sometimes a document that explains a decision is what clears someone of an allegation.

How do you interview fairly?

Interview the person who raised the concern first, then witnesses, then the person the allegations are about, then hold follow-ups to put new points to each side. Plan questions by allegation, offer adjustments and explain the right to be accompanied as your policy or local law gives it.

Use a simple structure: plan, engage (explain purpose, confidentiality and no retaliation), account (let the person tell it their way, then fill gaps with open questions), close (anything else, who else to speak to, next steps) and evaluate. Avoid leading questions such as 'he shouted at you, didn't he?' and avoid asking several questions at once.

The person accused must hear every allegation in full and see every piece of evidence that may be relied on, with a chance to respond to each. Record questions and answers, send notes for checking and keep any corrections alongside the original.

• Open: tell me, describe, explain, what happened next
• Closed, for detail: was that before or after the break?
• Leading: never
• For distressing accounts: explain what will happen, let the person tell it their way, ask once well, never imply blame, offer support

How do you weigh evidence and reach findings?

Most workplace processes decide facts on the balance of probabilities: is it more likely than not that this happened? Weight comes from independent corroboration, records made at the time, consistency over time and with documents, and inherent probability given everything else known. An early report to a colleague soon after the event supports consistency, though it is not eyewitness evidence.

Demeanour carries little weight. In a 2006 meta-analysis in Personality and Social Psychology Review, Charles Bond and Bella DePaulo pooled 24,483 judges across 206 documents and found an average of 54% correct lie-truth judgements, only a little better than chance. Reputation, seniority and gossip carry no weight at all.

Write one finding per allegation in five parts: the allegation, what is agreed, what is disputed with evidence numbers, how you weighed it, and the finding with a one-sentence reason. Where an allegation covers several occasions, decide each one; 'upheld in part' is a valid finding. Where a legal question arises, such as possible retaliation, find the facts and refer the legal question to an adviser.

Should you suspend someone during an investigation?

Only when there is a real risk to people, to evidence or to the investigation that a lighter step cannot manage. Suspension is meant to be neutral, but it rarely feels neutral to the person sent home or to colleagues watching them leave. Long suspensions isolate people and can damage health and reputations, so good-practice guidance in several countries treats suspension as a last resort.

Before suspending, consider and record alternatives: different duties, a different shift, team or site, supervised work, restricted access to a system or till, or working from home. If you do suspend, confirm in writing that it is not a sanction, keep the person on full pay unless the contract and local law clearly allow otherwise, name a contact who is not the investigator, and review the suspension at least every two weeks. End it as soon as the reason goes, which may be long before the case ends: once the till records are secured, for example, a risk to evidence may no longer exist.

What goes in the investigation report?

A good report lets the decision-maker, and anyone reading the file a year later, follow each finding back to the evidence. It contains a summary, the terms of reference, neutral background, how the investigation was carried out, the evidence, the findings per allegation with reasoning, a recommendation on whether there is a case to answer (the commissioning manager decides whether to proceed), any matters referred or escalated, and wider recommendations kept separate. Appendices hold the evidence log and the interview records.

The report should not recommend a sanction, describe conduct as gross misconduct or label anyone a bully. Those are judgements for the decision-maker applying the policy.

What happens after the investigation?

If there is a case to answer, the employee is invited to a hearing with the allegations, all the evidence, the possible outcomes and the right to be accompanied. An impartial chair hears each point, considers mitigation, checks how similar cases were treated and chooses a proportionate outcome, then writes it with reasons and an appeal right. The appeal goes to someone new, who answers each ground in turn.

Across the caseload, track timeliness, consistency by category and site (with a minimum group size of 5 so nobody can be identified), outcomes reached without investigation and appeals upheld. A learning review after each case is where an ER service gets better. Rules differ by country: one place to start is a dated set of law notes with official sources, and a legal adviser before any dismissal.

If you want every form, letter and tracker for this process in one place, the Employee Relations and Investigations Kit from Bodhih Training follows one case from complaint to appeal. To test how well you read caseload numbers, the AssessAll People & Performance Data Judgment assessment is a useful starting point, and a Jobulary individual development plan can turn what you learn into dated goals.