Chapter 18 finished last weekend. Chapter 19 finished yesterday. The murderer is named. The end is in sight. (Probably not before the children's winter break, however, but I'm taking my laptop to Disney World.)
Of course, there's still at least two more chapters to write. The next is the pursuit and comeuppance of the guilty party, solid comic action all the way, planned for years (to the point of photographing the attempted escape route, including the backstage interior of the Royal Shakespeare Theatre, on my last scouting trip to Stratford-upon-Avon. Google Earth is useful, too.) And then at least one more chapter for the wrap-up, because, being me, I've always got something else to say. Plus a major surprise for the regular cast members, to set up the sequel.
But Chapter 19 was hard going. This has been a big puzzle story. Without indulging in spoilers, I'll just say the plot presents a two-stage process for Oliver -- the first is to solve a set of mysteries that will identify the murder suspects, and the second is to decide which of them actually did the deed. Chapter 19 was this final stage -- and I had to make sure that every clue or hint or red herring I may have planted is all present and accounted for by now. (I actually use Word's highlighter feature to mark every clue as I write it, removing the color -- pink -- only when its resolved.)
You don't want the final accusation to be too wordy, with those "there's-just-one-thing-I-don't-understand-Inspector" asides. You want to show as much as possible rather than assert it. You don't want to sound as if your detective character -- or worse, you, the author -- are just parading your cleverness. (And I let Oliver make mistakes, even at this stage.) You don't want to save it all for this point, just those final details that may have obscured the culprit's true identity and/or motivation. Above all, you don't want to laboriously explain every tiny reference -- trust the readers' ability to fit a few of the jigsaw pieces into place without your help.
You aim for an effect that's like a baize-covered tabletop, on which there's a seemingly random scattering of beads. And as you pick up one, you find that another follows, and then another, and it's actually a well-ordered necklace on a fine nylon thread, clumsily thrown down, but regaining its integrity as it's lifted up to eye level.
I'm not sure I have that yet. That's why it's called a first draft.