From "Murdoch Mysteries: Unfinished Business (#7.12)"
[voiceover as Julia reads a letter from him
] My dearest Julia, it appears our relationship has yet to come to an end, but you can be rid of me once and for all if you agree to my most simple proposition. You and Detective Murdoch must part, forever. If you marry him, he will die. If you inform him of this letter you will both die. Yours most fondly, James Gillies.