" One of the first examples of forensic science solving a murder appears in a book called The Washing Away of Wrongs, published in 1247 by Song Ci, a Chinese coroner and detective. The author relates a story about a peasant found brutally hacked to death with a hand sickle. The local magistrate, unable to make headway in the investigation, calls for all the village men to assemble outside with their sickles; they’re instructed to place their sickles on the ground and then take a few steps back. The hot sun beats down. A buzz is heard. Metallic green flies descend in a chaotic swarm and then, as if collectively alerted, land on one sickle, crawling all over it as the other sickles lie undisturbed. The magistrate knew traces of blood and human tissue attract blowflies. The owner of the fly-covered sickle hung his head in shame. The case was solved. "

― Michelle McNamara , I'll Be Gone in the Dark: One Woman's Obsessive Search for the Golden State Killer