High Quality Content by WIKIPEDIA articles! The Casket letters were eight letters and some sonnets said to have been written by Mary, Queen of Scots, to the Earl of Bothwell, between January and April 1567. They were produced as evidence against Queen Mary by the Scottish lords who opposed her rule. In particular, the text of the letters was taken to imply that Queen Mary colluded with Bothwell in the murder of her husband, Lord Darnley. The authenticity of the letters, now known only by copies, continues to be debated. Some historians argue that they were forgeries concocted in order to discredit Queen Mary, and ensure that Elizabeth I supported the kingship of the infant James VI of Scotland, rather than his mother.