I'm struck by how many "hints" there are about the identity of the killer throughout the series so far. So many lines and moments now strike me as BIG HONKIN' clues. I've been restraining myself from ruining it for people in the column, because the temptation to point to details like "Don't you ruin this too," or the altered hair, or his spiralling madness, is almost overwhelming.
I know that no one, including Wise, knew in advance who the killer would end up being - but it sure feels as though Lynch and Frost knew it from the very first episode. Which is nice.