Alright, So I guess this is my last update on Pete. I put off making this post because I wanted to be certain before posting. As far as I can tell, Pete isn't with us anymore.
I haven't seen him in about a month. Mostly I would see him in the morning 2 or 3 times a week and then it jumped to almost daily. Then, about a month ago, I didn't. And it's that simple. I haven't seen a body, living or otherwise. I do have a very efficient bristle worm (he only scavenges) and I believe he did his job. That, and the fact he's a dwarf in a 75 gallon tank, make me doubtful I will find evidence one way or another.
Pete was definitely some kind of dwarf, and I believe he was an O. digeuti, so it isn't surprising. I had him roughly 5 months (that I can confirm). He was young when I got him, so it stands to reason that finished off his life cycle.
It's just sad to have such an anti-climactic end to my little guy! Thanks to everyone who followed along!
I suspect you have the correct diagnosis but there is one other possibility, though not a happy one. Pete may have been Petra and has denned up to lay eggs. However, since you have had her so long and from such a young age, the eggs would not be fertile. It is unlikely you will know though as the scavengers will do there job in the end. If she is brooding, you might see her one more time at the point (any time now) that the eggs would have hatched as the females will often leave their den and wonder about.