Capa's lost art finally exposed

To the untrained eye, it is just a tattered cardboard box, holding row upon row of photographic negatives. To photography experts it is part of the "Mexican Suitcase", a cultural legend that went missing for 70 years, containing the most enigmatic work of the acclaimed war photographer Robert Capa.

The "suitcase" is full of negatives of photographs taken during the Spanish Civil War, which were lost when Capa left Europe in 1939. They resurfaced in Mexico in the 1990s. For years, negotiations over who should take possession of the precious hoard dragged on, leaving curators, desperate to get their hands on the 126 rolls of film, in suspense and the images in limbo. Last December, they were finally acquired by the International Centre of Photography in New York. Now the excavation has begun.

"We consider this one of the most important discoveries of photographic work of the 20th century," Brian Wallis, the centre's chief curator, told The New York Times. "This really is the holy grail of Capa work. It does seem strange in retrospect that there weren't more efforts to locate these things. They were lost in the war, like so many things."

But Wallis and his colleagues were disappointed in their hope that the trove would solve the mystery that surrounds one of Capa's most famous images, The Falling Soldier. Taken in 1936, it apparently shows a Spanish soldier being killed – but so perfect is the image that many have suggested it was staged. The hope was that among the negatives might be some originals of that picture, which only exists in print form – and perhaps other shots from the same series that might answer the question. But none of the boxes contained the negative.

Nor is that the only mystery attached to the discovery. No one quite knows how the negatives found their way from Capa's Paris darkroom to Mexico. According to Capa's biographer, Richard Whelan, who died in 1997, Capa asked his darkroom manager, the Hungarian photographer Imre Weisz, to look after his negatives when war broke out. Capa left for New York and the boxes fell into the hands of a Mexican diplomat, General Francisco Aguilar Gonzalez, who was in Marseille.

The negatives went with Gonzalez back to Mexico and when he died in 1967, they were given to a film-maker in Mexico City, Benjamin Tarver. In 2007, after long discussions, he agreed to give them to the International Centre of Photography, founded by Capa's brother, Cornell Capa, in 1974. The institution will show the pictures in an exhibition next year.

As well as photographs by Capa, the boxes contain negatives of work by his contemporaries Gerda Taro and David Seymour. Taro was Capa's professional partner while Seymour, known by the nickname "Chim", went on to found the highly acclaimed photographic agency Magnum with Capa and the French photographer Henri Cartier-Bresson in 1947.

Capa was known by his peers as a risk-taking, sometimes glamorous artist. The American author William Saroyan wrote that he thought of him as "a poker player whose sideline was picture-taking."

But experts say one of the unexpected treasures in the discovery is Seymour's work. He was best known for his poignant portrayals of ordinary people touched by war, especially children.

"This really fleshes out for the first time our picture of Chim in Spain, and the work is truly a great accomplishment," Wallis said. "We were bowled over by how much of his work was in this." Chim is believed to be responsible for one-third of the negatives.

All three photographers died while working – Capa trod on a landmine in 1954, photographing the Indochina War – meaning that these images offer the best chance of resolving ambiguities about their work that remain. "To me that's what's so exciting about this material," said Wallis. "There are so many questions and so many questions not even yet posed that they may answer."