A rediscovered painting by Andrea Mantegna has been rejoined with its companion piece for the first time in centuries. The Resurrection of Christ is now on the wall above The Descent of Christ into Limbo at London’s National Gallery in its Mantegna and Bellini exhibition. The two works were originally the top and bottom parts of a single painting but were separated at an unknown time in the distant past.

The Resurrection of Christ panel painting has been in the collection of the Accademia Carrara in Bergamo for more than a hundred years. It had been in storage since the 1930s after art historian Bernard Berenson assessed it to be a late 15th or early 16th century copy of the lost original. In March of this year, Accademia Carrara curator Giovanni Valagussa was cataloging works in the collection created before 1500 when he noticed the painting seemed to be of very high quality for a copy. He was also intrigued by the unusual placement of a horizontal strut. These wooden supports were common in panel paintings to keep the wood planks from separating and warping, but they’re typically placed at the top and bottom of a painting, not in the middle. That oddly applied strut gave Valagussa the idea that the The Resurrection may have been part of a larger piece. Even for famous painters like Mantegna, artist in residence at the Gonzaga court in Mantua, Renaissance collectors were far more cavalier about cutting up artworks to fit their spaces and decorative motifs better.

When he examined the painting more closely, Valagussa found a key clue. In the bottom center of the piece, disguised by the inky darkness of the cave, there was a thin gold cross. It was just there; not connected to anything, almost a reflection of the cross at the top of the staff Jesus holds as he emerges from his tomb undeceased. He also spotted tiny cut marks at the bottom which had never been noted before.

The clues of the gold cross, the cuts and the wooden strut inspired Valagussa to seek out other known works of Mantegna dealing with the subject matter. He also had the panel’s surface infrared scanned. The CT scanner found that the soldiers’ full technicolor armor was painted over nude figures, a method Mantegna employed all the time.

With the evidence of a Mantegna authorship piling up, Dr. Valagussa sought out a possible work that would have been part of a large original. Jesus’ long weekend in Limbo between his death and resurrection was a popular subject often paired with depictions of the resurrection. Mantegna had made several paintings of Jesus visiting Limbo. One of them, now in a private collection after having been sold at Sotheby’s in New York for almost $30 million in 2003, also included a long staff in Jesus’ hand. When The Resurrection of Christ and The Descent of Christ Into Limbo were lined up to together, the gold cross of the former was perfectly perched on the staff of the latter, and the arches stones of the cave entrance matched up exactly.

Dr. Valagussa contacted Dr. Keith Christiansen at the Metropolitan Museum of Art, John Pope-Hennessy Chairman of the Department of European Paintings and the world’s foremost expert on Mantegna. Christiansen studied the work assiduously and conclusively attributed it to the master himself, not his workshop, not a copyist. It would be impossible for a copy to match the undoubted Mantegna work so precisely. It had to have been cut in half.

Since the painting’s true authorship was rediscovered, The Resurrection of Christ has been restored in preparation for display. The owner of The Descent of Christ Into Limbo, an anonymous private collector who is not keen to let his $30 million masterpiece out of his hands, was prevailed upon to loan it to the National Gallery so the two works could be reunited at long last.

Mantegna and Bellini runs through January 27th, 2019. Next March it will move to the Gemäldegalerie in Berlin.