The group shows the saleswoman the found jewelry and asks if it was purchased at "Gracia." If the answer is yes, they try to find out the identity of the buyer. This includes showing a photo and asking about the girl in it.
Added 4 minutes later
If I am sure that the painting is in the house, and the owner categorically refuses to allow access to his property, what should I do in this situation?
And what do you think about the options I listed?