During the reign of Emperor Gaozong of the Tang Dynasty, there was a renowned scholar named Wang Yifang, known for his uprightness, integrity, and fierce hatred of evil.
In the first year of the Xianqing era, Wang Yifang was appointed as an imperial censor. Within less than twenty days of taking office, he encountered an intolerable incident: Bi Zheng, the county magistrate of Dali, had hanged himself.
In Dali County, a murder case was under review where a woman named Chunyu was accused of killing her husband. The county magistrate Bi Zhengyi, being Chunyu's close neighbor, knew all about her loose morals and criminal deeds. The cunning Chunyu counterattacked, claiming Bi had an affair with her and that his testimony was fabricated to frame her—making him the real killer. Bi fell into a trap; despite repeated defenses, he was forced to hang himself to prove his innocence. Those in the know, seeing another life lost, dared not speak the truth.
When the case files reached the capital, imperial advisor Li Yifu, who had distant ties to the woman Chunyu, seized the opportunity to shift all blame onto the deceased Bi Zhengzhi, clearing Chunyu of any wrongdoing.
Li Yifu wrote his verdict: "Chunyu's crime lacks evidence and should be leniently handled; Bi Zhengyi committed suicide out of guilt and will not be pursued." Wang Yifang carefully reviewed the case files, found many suspicious points, and resolved to clear Bi Zhengyi's name. He reported to the emperor, "This matter cannot be decided solely by Li Yifu."
At that time, speaking such words required real courage. Who was Li Yifu? He had helped Emperor Gaozong of the Tang Dynasty make Wu Zetian his empress and was the emperor's most trusted favorite—who would dare offend him? But Wang Yifang, a principled official, reported to the emperor, "Your Majesty rules the realm and should personally hold the power of life and death. Even in the most remote regions, true criminals must face severe punishment. In this case, the witness is dead and will never testify again. But since doubts remain without sufficient evidence to resolve them, the investigation must continue—this case cannot be hastily closed."
Later, the truth was uncovered, and the murderer, Chunyu, was executed.
"The idiom 'kill to silence' means to murder someone to prevent them from testifying. Today it often refers to killing those in the know to conceal the truth."
Source: *New Book of Tang*, "Biography of Wang Yifang"
Meaning of the Idiom: Later, the Chinese idiom "杀人灭口" came to describe how to murder someone to prevent them from testifying.