Maybe I just don't know how to work this stuff, but I wasn't aware you were replying since you're doing it as AC. I get notifications when a replier is logged in, so you might consider logging in if you want to continue the exchange.
Sorry, which investigations found that no emails were deleted? Please provide the reference, along with the convincing evidence that no emails were deleted. It was my understanding that there was no way to know the answer to that, and that in at least one investigation the investigators deliberately avoided asking if emails were deleted because they didn't want anybody to admit to a potential crime. (To anybody paying attention, the investigations were for the most part an exercise in "friends helping friends out," and not particularly interested in stirring any pot that might turn up scandal and academic disgrace.)
I'm guessing the evidence that no emails were deleted consists of... what... not finding any deleted emails? LOL! Stick around and I'll explain the concept of "deleting" to you.