Yes. You need to be aware of all the facts so that you can make an informed and fair decision. Sometimes investigations will be very quick and just include gathering information (e.g. if someone is continually late for work you need to gather the attendance records/dates when they were late). Other times investigations may be more detailed and may involve having to interview other employees.  Refer to the guidance on investigations for more details and examples.

By law an employee can be accompanied by a colleague from the Company or a trade union representative (regardless of whether you recognise a trade union). 

Under discrimination law, employers must make reasonable adjustments for disabled employees. This might mean allowing someone else to attend, as a reasonable adjustment e.g. a support worker or someone with knowledge of the disability and its effects.

The manager or a senior person should generally conduct a disciplinary meeting.  You should refer to your own disciplinary procedure to see if it stipulates who will conduct meetings.  Some procedures may stipulate that a number of people must hear a disciplinary (a panel) and you should always endeavour to follow your own procedure. Remember that if the employee appeals someone else will need to hear the appeal, so you should make sure another manager or senior person is not involved in the disciplinary hearing, so that they can independently hear any appeal. 

Please see the sample disciplinary procedure and notes on managing disciplinary situations for further guidance.