Concerned a well respected preceptor might be diverting meds

Without going into too much detail, he has asked many of us to “witness” him wasting a med. I think he asks new grads because he assumes they won’t know better? when I told him I wouldn’t sign as a witness unless I physically saw him do it, he said it was fine because he had the medication sticker on the back of his badge. That seemed like a red flag to me-why do you have the sticker for a controlled substance on your badge? He said it was because we use it often. He also said that everyone does that, and that is most definitely not the case. The other weird thing is that the barcode is linked to an individual lot number and expiration date, so I feel like eventually management will catch that? I’ve also noticed him jumping to take patients that need this particular medication, and not allowing preceptees to give this medication saying he will “handle it”. Now granted I don’t have actual proof that he is diverting this medication…just a gut feeling. This is a well respected preceptor who has won a bunch of awards so I don’t want to say the wrong thing or make an assumption and have it be wrong…but I just have a feeling something is off here. Obviously I know I should tell management, but management adores this guy, and I just don’t want to get a target on my back as a new grad. I could use our anonymous reporting system, but this would mean all of our wasting for the next month would need to be done with a nurse manager, and would slow down us giving meds in the ED. I want to do the right thing. Any advice is helpful 🥺❤️