Maybe so, but will they be able to use it against Charlie? He clearly did not believe he was talking to two men functioning as policeman, so does recording it violate his civil rights? On the other hand, they clearly weren’t his lawyers either. If our story’s CPD uses the recording, but the judge throws it out, comma any charges that came from, it would have to go as well, as “fruit from the poisonous tree.“ they might need to set up a completely second lab to work with the new video evidence, not contaminating anything they learn from the search of Charlie’s apartment.
at least, that’s what my fictional detective intuition tells me.