According to research by the Vietnamese historian Phạm Văn Sơn, Tự Đức had intended for Kiến Phúc to succeed him, but that the regents installed Dục Đức under pressure from the Tam Cung. Tự Đức had criticized Dục Đức's morality in explaining his appointment of Kiến Phúc, information that the regents deleted from the will at the request of the new monarch. However, the regents were unimpressed by Dục Đức's behaviour after their reprieve and decided to execute him. The treatment of Dục Đức has since raised speculation among historians that it was a vengeance killing due to the monarch's interference in the affair between Tường and Học Phi.