What do you do if your investigative plan isn’t working? Let’s say you interviewed your reporting party, came up with an investigative lineup, and, those people have no idea what you are asking about. Let’s say your plan is just not working. Assuming you’re billing your client by the hour, you should cut your losses and acknowledge that you need a new plan
The other thing you need to do is write about what you did in your report. It could even be a footnote that says “initial reports indicated Betty, Tom, and Sue had pertinent information but investigative efforts did not elicit any helpful information.” You need to indicate why you spoke to someone whose information was disregarded or else your investigation could begin to look more like a witchhunt.
The organic nature of you pursuing a path and then redirecting to a smarter path is an intrinsic part of what shows your lack of bias and your neutrality as an investigator. A biased investigator would continue on a witchhunt despite a lack of results. Further, if you already knew the conclusion, you would just continue working in that direction until you found what you needed, right? The very nature of you having to step back restructure your investigative plan shows the unbiased and organic nature of the investigation you are conducting.