Thaddeus Ma Daqin is a Shanghai native. He was ordained a priest in 1994, upon his graduation from the Sheshan seminary. He was once the editor of the diocese's Guangqi Press, one of the two main Catholic publishers in mainland China.
He was elected Auxiliary Bishop of Shanghai on May 30, 2012. His episcopal ordination took place on July 7 the same year with both papal approval and government recognition. Before his election as auxiliary bishop, Father Ma served as head of Shanghai diocese's Pudong deanery. In mid-December 2011, he was appointed by Bishop Jin as vicar general.
In July 2012, Father Ma was appointed as auxiliary bishop with the approval of the Holy See and Chinese Government. He announced his resignation from the Chinese government sanctioned Chinese Patriotic Catholic Association at his episcopal ordination Mass, and was taken into custody as a result.
The Chinese authorities has detained him under house arrest ever since (largely confined to Sheshan Seminary) and has prevented him from carrying out his episcopal duties.