However, after the plot (later known as the Ganlu Incident) failed, Li Xun and he were both killed, along with many other officials that the eunuchs suspected of being complicit.
(As Yu means "fish" in Chinese, eventually, when Zheng became powerful, he was sometimes obliquely referred to as "the one from the water.
Later, when Li Su was moved to be the military governor of Wuning Circuit (武寧, headquartered in modern Xuzhou, Jiangsu), Zheng followed him, and became even more involved in the decisions.
At Zheng's suggestion, Wang Shoucheng, who was then the commander of one of the Shence Armies (神策軍), had Doulu Zhu, one of his officers submit an accusation that Song and Emperor Wenzong's brother Li Cou the Prince of Zhang were plotting to remove Emperor Wenzong and replace him with Li Cou.
Zheng was fearful that a thorough investigation would show that the accusations were not true, and therefore had Wang suggest to Emperor Wenzong that Song and Li Cou be spared; however, both were demoted and exiled.
Meanwhile, he was grateful to Wang Fan for having revealed Song Shenxi's plan to have him killed, and because Wang Fan was also friendly with Li Zhongyan (whose name was changed by this point to Li Xun), they jointly recommended that Wang Fan be recalled from his position as the governor of Zhexi Circuit (浙西, headquartered in modern Zhenjiang, Jiangsu) to serve as one of the secretaries general of the executive bureau of government (尚書省, Shangshu Sheng).
As a result, Emperor Wenzong ordered 1,500 Shence Army soldiers to dredge Qu River (曲江) and Kunming Pond (昆明池).
The junior censors Yang Jian (楊儉) and Su Te (蘇特) pointed this out and argued with him, and when he cursed them, submitted an accusation against Jia.
[2] (According to comments by the modern historian Bo Yang, this commission was Zheng's way of showing that he had the power to make people chancellors.
)[7] In summer 835, there was a rumor that spread throughout Chang'an that Zheng was making immortality pills for Emperor Wenzong, and the ingredients included infants' hearts and livers.
Meanwhile, Li Xun and Zheng mapped out a three-step plan for Emperor Wenzong to pacify the empire—first eliminate the eunuchs, then recover the lands lost to Tufan, and then wiping out the warlords north of the Yellow River, with details.
[2] Zheng also further revealed that Li Zongmin's initial commission as chancellor in 829 was due to his association with the female imperial scholar Song Ruoxian (宋若憲) and Yang Chenghe.
Li Zongmin was thereafter further demoted, while the official who was in charge of the investigation against Yang Yuqing, Shu Yuanyu, was promoted to be chancellor.
[2] In fall 835, Zheng requested to be the military governor of Fengxiang Circuit (鳳翔, headquartered in modern Baoji, Shaanxi), but the chancellor Li Guyan refused.
After Zheng arrived at Fengxiang, he submitted a report that accused Li Ting of being cruel and corrupt.
As a result, Li Ting was stripped of his post as the military governor of Zhongwu Circuit (忠武, headquartered in modern Xuchang, Henan).
When the eunuchs, led by Qiu Shiliang and fellow Shence Army commander Yu Hongzhi (魚弘志), arrived at the scene, Han's anxiety, as well as sounds of arms clanging, gave away the fact that the soldiers under Han, Wang Fan, and another associate of Li Xun's, Guo Xingyu (郭行餘), were about to act against the eunuchs.
They then mobilized the Shence Armies, and the Shence Armies slaughtered the troops aligned with Li Xun, and then killed a large number of governmental officials, including Li Xun, Wang Ya, Shu Yuanyu, and Jia Su, under the claimed crime that they were planning to overthrow Emperor Wenzong and support Zheng as the new emperor.
The magistrate of Fufeng County, Han Liao (韓遼), became aware of Zheng's plan, and therefore refused to supply him and fled to Wugong (武功, in modern Xianyang).
[2] His subordinate Wei Hongjie (魏弘節) suggested to him that he kill the eunuch monitor of Fengxiang, Zhang Zhongqing (張仲卿), as well as a number of officers, but Zheng, terrified, did not know what to do.