The Directorate of Professional Standards, the group of officers that investigate officers, some may say they lack understanding or empathy or even sympathy, but lets just call them the "OPPS" for now.
When dealing with this group of people you really need to be careful, they have the ability, the means and the authority to do whatever they like. From pressuring officers or convincing members of public to make allegations that aren't necessarily true.
There is little to no accountability or scrutiny when dealing with their tactics and investigations styles.
My advice would be if they ever contact you regardless of the nature of conversation CONTACT A FED REP ASAP!!
If you happen to get cornered by them, be brave and request your fed rep, or another officer to be with you as a witness.
I cannot stress how important it is to limit all interactions with these people is.