HONG KONG — Almost a year after the Chinese human rights advocate Chen Guangcheng made an audacious escape from detention in his home village, his family there remains under surveillance and his jailed nephew has said he was beaten and warned by officials not to challenge his conviction, Mr. Chen and his older brother say.

Mr. Chen, who is blind, catapulted to international fame in April, when he evaded walls, security cameras and guards who kept him under house arrest for one and half years in Dongshigu, a village in eastern China. Helped by supporters, he found refuge for six days in the United States Embassy in Beijing and left after Chinese officials agreed to let him study at a university and to investigate his complaints of brutal abuse by officials and guards.

But, worried that he and his family could suffer reprisals, Mr. Chen then asked to go to the United States, prompting testy negotiations between Chinese and American officials that resulted in his departure to New York in May, accompanied by his wife and two children.

Since then, Mr. Chen has repeatedly criticized the Chinese government as failing to live up to vows of rule of law and respect for rights. Now he and an older brother have described threats and surveillance that Mr. Chen said showed that tethers on dissent remain tight under the new Communist Party leader, Xi Jinping, who was appointed in November.