侯君集
The death of Li You drew out news of another plot. Li Chengqian, who had been fearful that Emperor Taizong would eventually remove him and replace him with Li Tai, had begun to conspire with Hou Junji, Li Yuanchang () the Prince of Han (Emperor Taizong's brother), the general Li Anyan (), and his brothers-in-law Zhao Jie () and Du He (, Du Ruhui's son) to overthrow Emperor Taizong. During the investigations in the aftermaths of Li You's rebellion, one of the co-conspirators, Li Chengqian's guard Gegan Chengji (), was implicated by association, and in order to save himself, he revealed Li Chengqian's plot. Emperor Taizong was shocked by the news, and he appointed Zhangsun Wuji, Fang Xuanling, Xiao Yu, and Li Shiji, along with the officials in charge of the supreme court and the legislative and examination bureaus of the government to carry out a joint investigation. At the suggestion of the mid-level official Lai Ji, Emperor Taizong deposed, but did not kill, Li Chengqian, while ordering Li Yuanchang to commit suicide and executing Hou Junji, Li Anyan, Zhao, and Du.