Agreed for the most part on returning serial killers.
I find that I need to look up the actor, and then I'm like, "That's it! That's where I know them from!" And some I feel weirdly invested in, like, "Oh, they've had a good career since then, good for them!"
For those who like this show, I do highly recommend "The Closer" and "Major Crimes." (though: returning serial killer warning!)