This is a judgment call based on many factors. For example if you record an interview it’s safe and it saves time, but you will need to make a file note or a summary of the interview so it can be annexed to the investigation report. In some cases you may wish to have an interviewed transcribed word for word, but this comes with a cost. Statements however are useful if the witness is some distance away or the information that they can provide is not controversial, simple and not in dispute.