Alright. To further my proof it was probably Orochimaru, here is what most likely happened. Orochimaru got some DNA from them all through scrounging the area after they fought a TB or something else. Any blood would've been fine, perhaps for future experiments. But he couldn't get Konan's because she was always with Pain, and also she was always paper, if you are paper, there is no real body. And he tried to go after Itachi once, but he was scared of the Genjutsu, so trying to go after Kisame, who followed Itachi nearly always, would've been impossible.
