Death of an Expert Witness is a detective novel by English writer P. D. James, the seventh of her Adam Dalgliesh series. It was published in 1977 in the UK by Faber and Faber, and in the US by Charles Scribner's Sons. Set in the Fens, it follows the investigation of the murder of a senior scientist at a police laboratory where his colleagues are too experienced to have left clues. Wikipedia