AGATHA CHRISTIE, bored with her detective, Hercule Poirot, killed him in a book called Curtain, written in the 1940s but kept hidden until 1975. Christie understood the implied contract between authors and readers, who become attached to regular characters. Now, three crime series have been brought to an end and we can expect mourning and, perhaps, some resentment.
Illustration: Rocco Fazzari.
The American writer Laura Lippman has won almost every award there is with her long-running series about private detective Tess Monaghan. Nevertheless, she is going to be in trouble with readers for the last instalment, The Girl in the Green Raincoat, in which we find Tess pregnant. Tess and her boyfriend finally settle into becoming a family and it is suggested that now she is to be a mother, Tess will stay at home. Lippman, who wants to concentrate on stand-alone mysteries, is drowning Tess in the domestic sink.  (Illustration: Rocco Fazzari.)

<i>The Girl in the Green Raincoat</i>, by Laura Lippman (HarperCollins, $19.99)Sometimes a crime series ends simply because there is nothing more to tell. Charlaine Harris's Lily Bard novels were not published here until their author became famous for the True Blood books. The result is that we can read them all as an omnibus volume, which will affect our sense of an ending.