牛僧孺
In 844, after Liu Zhen was killed by his own officer Guo Yi (郭誼), who then surrendered Zhaoyi to the imperial forces, Li Deyu wanted to use the opportunity to carry out reprisals against his political enemies, the former chancellors Li Zongmin and Niu Sengru, and therefore, even though no evidence was found at Zhaoyi that Li Zongmin and Niu were in secret communications with Liu Congjian, had Liu Congjian's secretary Zheng Qing (鄭慶) claim that Liu Congjian would burn letters from Li Zongmin and Niu after reading them. Emperor Wuzong had Zheng report to the Office of the Imperial Censors, and subsequently, Li Hui and Zheng Ya, handling the investigations, indicated that they believed Zheng Qing's accusations. In anger, Emperor Wuzong had Li Zongmin and Niu exiled.