Ming Dynasty in Jin Yi: Notes on the Mysterious Case of Zhengde

In the autumn of the fifth year of Zhengde, undercurrents surged in Beijing after the fall of Liu Jin. A floating corpse floated from the Jinshui River into the moat. There was no injury on the whole body, except for a three-inch long golden scorpion needle inserted deep in the ear hole - this was the strange poison of the Western Regions, "The Laughter of the King of Hell". Qian Feng, a member of the Jinyiwei family, was ordered to conduct an inspection, but found half an ivory waistband in the deceased's clenched palm. The pattern actually matched the standard of the guards at the house of Zhang Rui, the eunuch who was the chief eunuch. Who is the mastermind behind the scenes?