At a museum, most of us care about what’s on the front of the canvas. But not if you’re into solving mysteries, like Nicole Atzbach.

She’s curator at the Meadows Museum, at SMU.

“You can see it here on the upper right side of the stretcher is the alpha-numeric code the Nazi’s assigned to the painting,” said Atzbach, while looking at the back of a 350-year old painting called Saint Justa by the Spanish artist Murillo.

Ten years ago, the Meadows learned two masterpieces in its collection, Saint Justa and its companion piece Saint Rufina, were once stolen by the Nazis.

On the back of the paintings are marks, now faded, that show Hitler’s inventory code. It’s known as an ERR number.

Records show the paintings were legally returned to the French government and legally obtained by the Meadows in 1972.

But the mystery remains. Who actually owned the paintings? And did they ever get them back?

“I wanted to know. Absolutely. They’re important works of art,” Atzbach said. “So, I figured there had to be a trail so I went after it.”

The first clues were the ERR codes R-1770 and R-1771. In the Nazi catalogue, the “R” stood for the prominent Rothschild family from Paris. So Nicole went to France, looking for a Rothschild.

It was dead end after dead end until a clerk gave her the wrong box of records. And that’s how she accidentally found a folder in the L’s, full of information about a woman named Antoinette Leonino. On it was a post-it note that said Madame Leonino equals Rothschild.

Leonino was a Rothschild. The Rothschild.

From what Atzbach found, Leonino was a huge art collector, who survived the war and her two paintings, Justa and Rufina, were returned to her by the Allies.

“I’m fascinated by her and I just want to learn her and her collection,” Atzbach said.

And there may be more moments of discovery out there.

That's because Atzbach’s findings could crack the code for hundreds of other works, owned by Antoinette, stolen by the Nazis and now spread around the world.