A close-up of Ramirez
In the basement is Ramirez, counting his loot.
You don't want to alert him, somehow, so you need to sneak past him.
If you have done it right until the time that you reached the
counting room, you have to face only Ramirez (and the Servant from
the kitchen here and then). Sit in the shadow at the table, and
observe his patrol pattern.
Hint - i.e. the shadow just ahead of you (from where
you can easily grab key, potion, and flashbomb, read the book, and
unlock and open the chest) is a good place to hide. But make sure
that you don't sit immediately on his patrol point.