Henry Stafford, Duke of Buckingham was a close ally of Richard III. He also had a tentative claim to the throne, which would be strengthened by the Princes’ death. A contemporary source noted that the Princes were “put to death in the tower of London by the vise of the Duke of Buckingham,” though historians debate the meaning of the word “vise.”
He may have had the boys killed to benefit Richard, but it is also possible he ordered the murder knowing Richard would be blamed, causing the country to turn against him. He eventually betrayed Richard and was executed.