By this time, Princess Elizabeth had become Queen Elizabeth I. Although she was the daughter of Henry VIII, many people - including most Catholics - thought Elizabeth was not the rightful heir to the throne. As the daughter of the discredited, beheaded Anne Boleyn, Elizabeth was thought to be illegitimate.
To strengthen her claim to the English throne, Mary decided to marry her cousin, Lord Darnley (Henry Stuart) who himself was an heir to the English throne. Mary and Darnley married (this is their marriage certificate), but the strategic alliance carried a high price. Darnley was no Francis. The marriage was extremely unhappy.
Notwithstanding all of his own scheming and philandering, Darnley was a jealous husband. When he thought Mary was having an affair with her secretary, David Rizzio, Darnley engineered Rizzio's murder. Not content to just kill him, Darnley and his compatriots stormed into
Mary's private quarters at Holyroodhouse and killed Rizzio in her presence. Even though Mary was expecting Darnley's child, a son, the marriage was doomed from that point forward. Perhaps it had been doomed all along.
Darnley was ill with syphilis. He was murdered within two years. Many people pointed to Mary as the engineer of the plot to kill Darnley. Since her current lover - and later husband - James Hepburn, the 4th Earl of Bothwell, was accused of planning Darnley's death, circumstantial evidence against Mary initially seemed strong.
But as the investigation continued, there was no solid evidence against Mary, Queen of Scots. Not - that is - until someone found a small, silver casket containing letters ostensibly written by Mary. Those letters seemed to point a guilty finger in her direction. Even though the letters were alleged to be forgeries, many people continued to believe she had ordered Darnley's death. And, even after a trial formally cleared Bothwell, most folks continued to believe he was the one behind Darnley's murder.