Vietnam's authorities have summoned pro-democracy campaigner and human rights defender Ngo Duy Quyen to a police station for interrogation on his posts on his Facebook account, the activist told Defend the Defenders. According to the police's summoning letter dated on June 1, Mr. Quyen, 44, must be at 8.30 AM of June 2 to work with Hanoi's police about the content of his recent posts. Quyen denied to go to meet with police officers on Saturday but he may face detention in coming days. The police's move came five days after Quyen posted a status calling Vietnam to arrest Lieutenant General Duong Minh Hung, deputy chief of the General Department of Security under the Ministry of Public Security, who is reportedly sought by Germany's authorities on relation with the kidnap of former Vietnamese senior officer Trinh Xuan Thanh in Berlin last July. According to Germany's media, Gen. Hung is likely the key figure designing and implementing the illegal detention of Thanh, a former executive of an affiliate company of the state-owned PetroVietnam. Thanh fled to Germany and applied for political refugee before being kidnapped by Vietnamese secret agents. After Thanh appeared in Vietnam's national television, Germany investigated the case and found many Vietnamese diplomats involving in the kidnap. The government of Germany expelled two diplomats working in Vietnam's Embassy in Berlin. It was reported that Germany's authorities issued international arrests for a number of Vietnamese officials, including Gen. Hung. It is not the first time Quyen is summoned by Hanoi police in relation with his social activities. He has participated in many peaceful demonstrations, including 11 gatherings in Hanoi in 2011 to protest China's violations of Vietnam's sovereignty in the East Sea (South China Sea). He got arrested many times in these events. In 2016, he was detained twice by Hanoi police after he, on behalf of a group of activists sent a joint petition which demand to investigate police power abuse to authorities in the capital city.Police also threatened him and his family after searching his private residence and confiscated a number of things, including computers and money. They still keep these items and money. Mr. Quyenis the husband of prominent former political prisoner Le Thi Cong Nhan and an older brother of former prisoner of conscience Ngo Quynh. Due to his political activities, he has been suppressed by local authorities. Under police's pressure, Quyen was forced to quit his job as legal expert in a law company. He tried to work in other fields, however, he was forced to abandon them because he cannot tolerate with systemic corruption among state officials. Finally, Quyen returned to his home town in Bac Giang, and together with his brother Quynh, he set up an organic farm for production of chicken, ducks, fish and vegetables. His high-quality products meet high demand, and he became regular supplier of safe farm produce for social activists in Hanoi and adjacent localities. Quyen is a key member of a charity organization named BauBi Tuong Than (People Solidarity)which has granted financial assistance for prisoners of conscience and their families as well as land petitioners. The unsanctioned human rights organization has provided limited but valuable supports for hundreds of activists nationwide.