Finding out the relevant facts is an important responsibility for any employer. The fact-finding exercise should include interviewing the accused employee about any alleged misconduct, so that they can explain what happened and why. The investigator will also need to interview enough witnesses to enable the investigator to decide what must have happened.
An investigation will not be fair unless the person accused has been given a proper chance to comment on all the allegations made against them and to put their side of the story. Anyone subject to an investigation must be given copies of any relevant evidence, before any disciplinary hearing takes place, in enough time so that they can adequately prepare.
The evidence depends on the facts and the type and seriousness of the allegations being made. As well as copies of witness statements from co-workers, relevant evidence might include, for example, CCTV evidence or social media posts. You should be given the chance to view the CCTV evidence in private with your trade union rep. You should also be given a copy of any texts, posts or emails being relied on.
You should speak to your union rep as soon as possible if you have one. You do not normally have a right to be accompanied to the investigation meeting unless this has been agreed by your employer. By contrast, all workers have the legal right to be accompanied by a work colleague or trade union rep to the disciplinary meeting and to any appeal.
It is sensible to make a careful chronological note of all you can remember of the incident, as well as a note of other factors that you think might be relevant for example, any extra stress you have been under at work, any unclear management instructions, any evidence that you might be being picked on or discriminated against, or any external factors that might make this incident a one-off, such as problems at home.
Other helpful evidence could include examples where similar behaviour by other members of staff has not resulted in a disciplinary investigation, and evidence of your good performance to date.
Ask your employer for a copy of the disciplinary rules and speak to your trade union rep as soon as possible if you have one.
It is a good idea to start keeping a diary, and to make your own notes of what is said for example in investigation meetings and meetings with management concerning the incident.