i like to say it is boston's last best secret. >> reporter: boston's last best secret. who stole the 13 works of art from the isabella stewart gardner museum? and where are they now? it is a question that continues to puzzle museum security director anthony amore. what is it about this case that keeps you up at night, that just doesn't sit right with you? >> there were lots of quirky things about it. every time you turn around there is a different interesting fact that you find. >> reporter: one of the biggest questions for amore -- why did did the thieves steal what they did? remember the path of the thieves on the second floor? when they went from the dutch room to the short gallery, they bypassed valuable works of art that were small and portable. and worth a lot more than some