The most funny thing is that sometimes the museum workers know where the stolen paintings are, but they don't want to be in any trouble by saying who has them.

The most funny thing is that sometimes the museum workers know where the stolen paintings are, but they don't want to be in any trouble by saying who has them. Maybe it's not true for the AAA-tier paintings, but those smaller ones, less popular but still valuable and with historical heritage, could be tracked, in theory. There was this one case near the place where I live, where a retired oldtimer who was very politicaly influential in his prime time had a few paintings, matching the paintings of the museum 100 kilometers away. When the museum worker was confronted about the missing paintings, the worker did not want to continue the conversation and quickly went away. The retired oldtimer is not with us anymore, so I imagine the paintings were moved to another members of the family. But tracking them would be rather easy. OTOH, retreiving them wouldn't be easy at all.