Di Renjie judged that Lu Cheng might be the real Yuan Tiangang through Yuan Tiangang's papyrus. To be specific, after Yuan Tiangang was rescued, he exchanged identities with his servant Lu Cheng and helped Di Renjie break through the Snake Spirit's headquarters with Lu Cheng's identity. After that, Yuan Tiangang hid in a snake cave on Dayang Mountain and pretended to be Lu Cheng. Meanwhile, Lu Cheng was invited by Xiao Qingfang to the headquarters to continue playing the role of Yuan Tiangang. When Di Renjie spoke to Lu Cheng, Lu Cheng casually revealed the truth of the falsified Luohe Stone Stele that only Emperor Wu Meiniang and Yuan Tiangang knew, which aroused Di Renjie's suspicion. Therefore, Di Renjie found out that Lu Cheng was actually Yuan Tiangang in disguise by comparing Lu Cheng's behavior and words with the real Yuan Tiangang.
Not long after Yuan Tiangang was rescued, he exchanged identities with Lu Cheng. The exact time was not mentioned.
The exact time when Yuan Tiangang and Lu Cheng exchanged their identities was not explicitly mentioned. Therefore, it was impossible to determine when Yuan Tiangang became Lu Cheng.
Yuan Tiangang appeared in the 30th episode of the TV series Detective Di Renjie. In this episode, Yuan Tiangang was captured and defeated by Li Siyuan. However, the search results did not provide any detailed information about Yuan Tiangang's plot and events in episode 30.
Di Renjie and Yuan Tiangang were not from the same dynasty. Yuan Tiangang lived in the end of the Sui Dynasty and the beginning of the Tang Dynasty. He had been an official in the Sui Dynasty and the Tang Dynasty. Di Renjie was an active figure during the reign of Emperor Gaozong and Emperor Wu Zetian, the sons of Emperor Taizong. Although the two of them had lived together for some time, they were not from the same era.
Yuan Tiangang was captured in the 29th episode of Detective Di Renjie 2.
Yuan Tiangang's ending was in the 29th episode of Detective Di Renjie 2.
In Detective Di Renjie 3, there was no clear information on how Di Renjie saw through Lu Jiying. We only know that Lu Jiying framed Li Han, swindled the secret letter, and informed the sect master along the way. However, the Ning Clan and Di Renjie finally saw through him. The specific process was not mentioned. Therefore, we can't get a definite answer about how Di Renjie saw through Lu Jiying.
In Detective Di Renjie 3, Di Renjie saw through Li Han through Lu Jiying's actions of framing Li Han, obtaining secret letters, and informing the sect master along the way. Although Lu Jiying had deceived almost everyone, thanks to the wisdom of the Ning family and Di Renjie's meticulous mind, he finally discovered Lu Jiying's true identity. The specific process was not mentioned.
Di Renjie and Yuan Fang were two characters in the TV series Detective Di Renjie. Di Renjie was the protagonist of the drama, a wise detective who solved many complicated cases through analysis and reasoning. Li Yuanfang was Di Renjie's right-hand man and guard captain. He was skilled in martial arts and was good at using the chain saber and the Youlan Sword. He was arrogant and strict with etiquette, but at the same time, he was childish and mischievous. These two characters worked together in the drama to solve various mysteries and became the favorite characters of the audience.
The Empress of the Great Tang asked Di Renjie to find the Phoenix Seal.