I misremembered about the final book:
... "I finished him off five years ago. That's to say, the final novel in the series of Montalbano is already written and deposited at the publishing house. When I get fed up with him or am not able to write any more, I'll tell the publisher: publish that book. Sherlock Holmes was recovered …" – with his cigarette-free hand, he mimes the detective being pulled from the water – "but it will not be possible to recover Montalbano. In that last book, he's really finished." ..
So presumably the tv company dont want to make that into a tv programme!