I am in Arneson's Master Bedroom and all items listed in the walkthrough for the bedroom have been examined and picked up (including the lemon tree on the porch which I picked up), and no safe has been revealed. Where is the safe located?

wicknext

Have you peeked at MaG's walkthrough, wicknext?

Gil.

This is a really picky part of the game.

The safe is behind a portrait in the Master bedroom. When Holmes has investigated everything both inside and outside the house, then Watson will shout out to him that the safe has been revealed. It will happen automatically -- the portrait will swing back. Very likely you won't even be in the room at the time, you'll just hear Watson's yell.

It's likely just one footprint or bloodstain that you've missed examining in close-up.

Thank you Rushes. That is very helpful!

I will go back outside and see what I missed.

Wicknext

Good luck and keep us posted!