Originally posted by the Voice of America. Voice of America content is produced by the Voice of America, a United States federal government-sponsored entity, and is in the public domain. China Releases Professor who Criticized President Xi, Friends Say Reuters BEIJING - A Beijing law professor who has been an outspoken critic of China's President Xi Jinping and the ruling Communist Party was released on Sunday after six days of detention, his friends said. Xu Zhangrun, a constitutional law professor at the prestigious Tsinghua University, returned home on Sunday morning but remained under surveillance and was not free to speak publicly about what happened, one of his friends, who declined to be identified, told Reuters. Calls to the media departments of the Beijing police and Tsinghua University seeking comment went unanswered on Sunday. .