Sometimes there is no way around it..........how do you come out to investigate a complaint, especially about animal cruelty, without admitting there was a complain. VERY OFTEN, the animal control doesn't tell them......but they guess correctly or claim AC confirmed it. It's not rocket science....if you are fighting with your neighbor and someone makes a complaint about them, its not hard to guess who made it.
People used to claim all the time that we had told them who complained. We didn't. But they already "knew" who would have done it and would lie and say AC told them and then the people would usually admit it.