The dissident who was at the center of a standoff between China and the United States on Wednesday accused Beijing of failing to live up to its promises as US lawmakers rallied behind him.Chen Guangcheng, a blind activist who was jailed after exposing abuses in China's one-child policy, has lived in New York since May 20 after a dramatic escape from house arrest to the US embassy in Beijing.Visiting Congress in his highest-level contact yet with the US government, Chen voiced concern for his nephew who was arrested soon after the dissident fled China's eastern province of Shandong for Beijing."The Chinese central government explicitly promised me that it would thoroughly investigate the extended oppression and abuse that I endured in Shandong province," Chen, flanked by lawmakers, told reporters in the Capitol."The government further promised to provide for the security of my family. However, it has been more than three months and I have not received any news on the progress of this investigation or even whether it has commenced," he said.Chen complained that no Chinese official has contacted him since he arrived in the United States. China had said that it was allowing Chen to go abroad with his family to study, but some experts presumed that China's main motivation was to get rid of Chen and doubted he would be able to return.Authorities have charged his nephew, Chen Kegui, with attempted murder. The dissident said that his nephew was defending himself with a kitchen knife after thugs liked to the local government broke into his home.Speaking before a meeting with US lawmakers, Chen said that the human rights situation was deteriorating in China but that change was inevitable as citizens and civil society make their voices heard."I sincerely hope that the United States and all other nations that embrace the fundamental values of constitutionalism, democracy, freedom and the rule of law will support and assist with a smooth transition in China," Chen said.