The best Patricia Cornwell books follow Kay Scarpetta from a Richmond morgue in 1990 to her newest high-tech cases, so the real choice is where you start. Her early novels run on microscopes, paper files and a chief medical examiner fighting for respect, while the recent ones bring in surveillance gadgets, family stakes and her niece Lucy's computer skills. One of her newer books drops fiction altogether and tells her own story.
Start with Postmortem, the Richmond strangler case that introduced Scarpetta and still explains who she is. Anyone more curious about the author than the character should pick True Crime, a memoir that traces Cornwell from a hard childhood to the morgue job that gave her the material for every novel since.
Scarpetta ages along with the books, so a nineties novel and a 2020s novel feel almost like different series: tight Virginia procedurals early, bigger conspiracies with personal fallout later. The useful decision is whether you want the classic morgue-and-microscope cases or the newer, gadget-heavy ones, and whether a nonfiction detour belongs on your pile.