Here are some of the costume designs.
And the roughs for the comic.
You may have noticed that the knife doesn’t exist in any of the sketches. It was added as an afterthought. Originally, I didn’t think it was necessary to show the murder weapon but changed my mind the day after I drew the strip.
If you’ve never seen the opera and get a chance to, I highly recommend it. Personally, I’d love to go to another one some day but it’s really just too expensive for me.