Seems to me that when you've got a "know it all" guy in the room -- a guy willing to talk-talk-talk, a reprehensible crime that is definitely a DP offense, you make damm sure you are double-covering all the bases, making sure his words are not muffled and the volume is solid, you probably ask him the same questions in different ways just to be sure he understands the questions, etc., etc., etc. These guys have seen it all, and they know what they're doing, and, believe it or not, they are indeed smarter that he is by miles.
And when he confessed, they certainly were aware of Rule35, and they made sure they could back it all up with proper procedure.
IMHO, Mr. I-don't-like-it-here is ******.