Death of an Expert Witness is an Adam Dalgliesh novel by P. D. James, published in 1977. It begins with the discovery of a murder of a young girl. However, this is not the focus of the novel, but rather is used as a method to introduce the reader to the staff of a forensic laboratory, the background of this mystery. The actual murder of Dr. Lorrimer, an experienced expert witness, is only discovered in the second section of the book.