The daughter of Hong Kong bookseller Gui Minhai, detained in China since November, has asked the U.S. to exert additional pressure on the Chinese government to secure his release. During a congressional hearing in Washington D.C. Tuesday, Angela Gui said her father — a naturalized Swedish citizen — had not been allowed legal representation during his eight-month detention, Reuters reports. “The U.S., Sweden, and other countries … need to work to make sure that Chinese authorities are not allowed to carry out illegal operations on foreign soil,” she said. Gui, co-owner of Hong Kong-based publishing company Mighty Current Media, disappeared while in Thailand in October, later appearing in police custody in Mainland China.