I find them all (the murder book, the knife and letter from that duke) but she has good explanations for them and Aureus basically says the same when i try to present those as evidence. Resulting in not being able to blame her or arrest her.
Which was one of the reasons i suggested maybe having such false positives - getting other NPCs arrested, as one of the ways to theoretically maybe make the murder quest more diverse for consequent playthroughs. LarQ (that is Swen i believe?) chimed in and said that may be only done as a mod, though.