Today, while I was reading through this hignly amusing Mystery House solution, it struck me. The killer wasn’t Daisy, it was the player character all along. The hair and the flower were just fake evidence he/she planted to frame Daisy, and the reason Daisy wanted to kill the player was entirely self-defense, as at that time he was done with everyone – including Joe, whom the player can murder in clear conscience, despite him being innocent, just doing his job! Some more evidence – remember the ending, when you leave the house full of dead bodies with the jewels? Doesn’t look like a detective’s job done right. Also, this “guru wizard” rating looks more like “master of trickery” than “master detective” to me.
Last thing, those notes, mostly painfully obvious. My hypothesis is that the player character suffers from short-term memory loss, so he writes those notes to himself (like in Memento, though the movie was made much later). It also helps to understand why we don’t remember most killings.