The picture probably dates from some time in the 1930s, after the Nazi Party's rise to power in Germany - but this was on the other side of the world.

"Nothing explained the presence of a swastika here," says Jose Ricardo Rosa Maciel, former rancher at the remote Cruzeiro do Sul farm near Campina do Monte Alegre, who stumbled across the photograph one day.

But this was actually his second puzzling discovery. The first occurred in the pigsty.

"One day the pigs broke a wall and escaped into the field," he says. "I noticed the bricks that had fallen. I thought I was hallucinating."...