Death of an expert witness

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 by 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. It is quickly established that only people associated with the lab would have the opportunity or the knowledge to commit the crime, which allows the detectives to focus their attention.