1. The chauffeur, Suzaka-san is a lady, but she looks like and dresses like a man. Coincidentally (?) the girl (Kaede) is a tomboy girl. Hmmm.
2. Katayose (victim) has a habit of not stirring the milk in his tea. Instead he waits for it to disperse.
3. The house is full of trick art: painted corridors, painted forest with real trees in front, and a false perspective road.
4. Kaede has been targeted. Freak car(shown) and hole in the garden(not shown, mentioned by Ogita), tree house rope ladder cut (shown when Conan was climbing).
5. Kaede was adopted from her uncle in Hokkaido, rather forcefully. Katayose said that Kaede's grandma was his good friend. Kaede couldn't confirm.
6. Nobody was seen coming out of the crime scene. Ran was at corridor and Conan+Kaede at the garden.
7. First finder is Conan, when he heard a groan from the room.
Now, my attempt at deducing what's going on:
Why?
[spoiler]1. She could be Kaede's real mother or her blood relative who probably had some sort of history with victim.
- Kaede was adopted from Hokkaido. It is certainly not just an act of random charity
- Kaede seemed to be loved more than the 2 others
-Suzaka loves Kaede very much
- She is well trusted by Katayose and Kaede
2. The letter code probably does not lead to a treasure, but to a dark secret (e.g. dead body? Memento? Confession letter?), which Katayose wants hidden for as long as possible (therefore he left the letter in Suzaka’s care “indefinitelyâ€





