BEIJING—Chinese authorities are putting the nephew of legal activist Chen Guangcheng on trial Friday in a case widely seen as retaliation by local officials angered by Chen's daring escape from house arrest earlier this year.

Chen Guangcheng slipped out of his tightly guarded village in northeastern China in April, fleeing to the U.S. Embassy and setting off a diplomatic tussle between Beijing and Washington. The activist, who is blind, now lives in New York.

Chen's nephew Chen Kegui, 32, faces charges that he assaulted officials who stormed into his house looking for the activist and will stand trial at the Yinan County People's Court on Friday afternoon, said his father, Chen Guangfu. The court confirmed the timing of Chen Kegui's trial.

The charge of "intentional injury" centers on a clash between Chen Kegui and local officials who burst into his home looking for Chen Guangcheng after his escape. Chen Kegui allegedly hacked at the officials with knives after he and his parents had been beaten.

Chen Guangcheng, in an interview from his home in New York where he has been studying English and law, said he was worried about his nephew's fate in the hands of China's opaque judicial system.

"This has shown clearly to the whole world that people should not pin even the littlest bit of hope on this system," Chen told The Associated Press. Chen said authorities in his hometown were acting "unreasonably, illegally and in violation of humanity."

Chen's flight from abusive house arrest in Shandong and into the protection of U.S. diplomats—which led to an agreement with Beijing to let him study in the U.S. accompanied by his wife and children—exposed the impunity of local officials and embarrassed the central government.

Supporters of Chen, who exposed forced abortions and other wrongdoing by local officials, fear that his relatives are at risk of retribution from local officials angry at Chen's escape.

Critics and the activist's supporters say that the case against Chen Kegui has been riddled with irregularities.

In the months since Chen Kegui disappeared into police custody, Yinan authorities have not officially notified his family about the prosecution nor issued an indictment or other official documentation to them. Officials have not let family members see Chen Kegui or hire their own lawyers to defend him, saying instead that Chen had accepted legal aid and court-appointed lawyers.

Chen Guangfu said he learned about the opening of his son's trial when the officially appointed lawyer called him Friday morning. "From the very beginning, they have not told us anything about the case," he said.

He stood by his son's innocence. "In our view he was acting completely in self-defense. They can say whatever they want, but that is how we see it," Chen Guangfu said. It was unclear if he would be allowed to attend his son's trial, but he said he would go to the courthouse, located in the county seat, an hour and a half by bus from his village.

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Associated Press reporter Isolda Morillo contributed to this report.