Begin the instructions to the witness by stating:
This is a workplace investigation. It is a serious matter. You have been asked to assist us. We are trying to find out what happened here so we can advise management accordingly. We appreciate your time and cooperation.
If the investigator is an attorney and the investigation is being conducted under the attorney-client privilege, provide the Upjohn warning. Regardless of whether it is appropriate to provide the Upjohn warning, the investigator should inform witnesses as follows:
Please know that I am a lawyer for the company. I represent the company. I do not represent you. I may share this information with organization management.