Chen Guangfu's son has been in police custody since last month, when he used a knife to fight off a group of plainclothes officers who broke into the family home in search of his uncle, Chen Guangcheng.
The New York Times reported Chen Guangfu traveled from his village in Shandong province in northeastern China to Beijing to advocate for the release of his son.
"Legally, Chen Guangfu is a free man but in reality guards have been preventing him from leaving his village," said Ding Xikui, a lawyer who met with him.
Chen Guangcheng, known as the "barefoot lawyer" for his legal fight against China's family planning laws, prompted a brief diplomatic crisis between China and the United States when he escaped from house arrest April 22. After climbing over the village walls, Chen was smuggled into Beijing through a chain of human rights activists.
U.S. Secretary of State Hillary Clinton approved a request to smuggle Chen into the U.S. Embassy April 25, agreeing to shelter him as a "diplomatic quandary."
Chen and his immediate family were granted U.S. visas and departed the country May 19. Chen accepted a visiting scholar position at New York University to complete his legal education.