"By God's will, after a long voyage from the island of Greenland to the south toward the most distant remaining parts of the western ocean sea, companions Bjarni and Leif Eriksson discovered a new land . . . which they named Vinland." (partial translation of caption in upper left corner)

Italy, Spain, England, and Ireland are among the countries depicted on this 11" x 16" map at Yale University. If authentic, it would be the earliest map, 50 or so years prior to Columbus's voyage, to depict the North American continent; on the upper left is what is taken to be the coast of Newfoundland. While carbon-14 analysis dates the parchment to around the 1430s, chemical analysis suggests the ink dates to around the 1920s; the debate is far from over.

Consider the two conflicting studies that appeared in scientific journals in August 2002. One, published in Radiocarbon, gives a date for the map's parchment of 1434, suggesting to the researchers that the map could well be authentic. The second study, published in Analytical Chemistry, comes to the opposite conclusion, arguing, as previous studies have, that the presence of a mineral called anatase in the map's ink indicates a 20th-century origin—even if the parchment is far older. And in September 8th's Boston Globe the rival factions were rehashing the debate once again.

But now the forgery camp may have some fresh ammunition. A Norwegian historian says she has fingered the forger: a German Jesuit priest named Josef Fischer, whom she believes made the map partly to protest the Nazi regime.

"He would have made the map not for profit and not to flaunt it publicly, but mostly as a private protest," said historian Kirsten A. Seaver, an independent scholar based in Palo Alto, Calif., who is the author of a well-regarded book about the Viking exploration of North America [The Frozen Echo: Greenland and the Exploration of North America, ca. A.D. 1000–1500, Stanford University Press 1996]. "I'm very convinced it was done to tease the Nazis."

Politics and religion are at the heart of Ms. Seaver's intricate case against Fr. Fischer, which she has laid out in several scholarly articles and is turning into a book that she hopes to publish next year. And though her evidence is mostly circumstantial

"He was in pretty much the right place at pretty much the right time and had the right information," concludes one scholar about the possibility that German Fr. Josef Fischer, SJ, concocted the Vinland map in the 1930s. Fr. Fischer, the thinking goes, could have relied on his knowledge of history and cartography to create it and then "salt" it with subtle Catholic overtones, his way of blunting Hitler's propagandistic efforts to link the fortunes of the Nazis to their supposed Nordic forebears and their common desire for lebensraum.

"He seems pretty plausible," said Robert W. Karrow, curator of special collections and maps at the Newberry Library in Chicago. "It may have been intellectual arrogance or just a game, but he was in pretty much the right place at pretty much the right time and had the right information. I think it all hangs together."

As Ms. Seaver points out, in many ways the Jesuit is an obvious suspect. He was an avid scholar and collector of old maps, credited with discovering the now legendary Waldseemüller world map from 1507—the first to use the word America.

He was also passionately committed to the idea that the Norse had been to this continent long before Christopher Columbus, publishing a book on the subject in 1902. At the time, there was little evidence for Fr. Fischer's theory. Yet he was convinced a cartographic record of the venture must exist.

These facts alone might qualify as probable motive, but Ms. Seaver's theory is more elaborate. Fr. Fischer, she argues, would have been outraged by the Nazis' persecution of Jesuits.

In 1938, Nazi officials forced the sale of Stella Matutina, the Jesuit College in Feldkirch, Austria, where Fr. Fischer had taught and was living in retirement. (He moved to Munich the next year and died in 1944.)

At the same time, Ms. Seaver contends, Fr. Fischer would have been appalled to see ancient Norse history put to use as Nazi propaganda. The Third Reich did a bustling traffic in ersatz Norse art and artifacts, she points out, as German officials saw in the Vikings an Aryan people with territorial ambitions much like their own. In particular, a Viking conquest of North America would supply a perfect rationale for the Reich's empire-lust overseas.

By making the Vinland Map, Fr. Fischer would thus seem to be fulfilling a cherished Nazi dream. But—and here's the rub—the map is laden with Catholic imagery. The legend in the top left corner refers not only to the discovery of "Vinland" by "the companions Bjarni and Leif Eriksson," but to a trip there soon after by Eric, "legate of the Apostolic See and the bishop of Greenland."

This, Ms. Seaver argues, was Fr. Fischer's ruse: to give the Nazis—and history—a Viking conquest of the New World but to make clear that it was a Catholic one as well.

Stella Matutina, the Jesuit school in Feldkirch, Austria, which opened in 1901, is where Fr. Fischer taught and later lived in retirement. The Nazi Party expropriated the school in 1938, using it first as the Reich's school of finance and later as a military hospital. Historian Kirsten Seaver's theory is that Fr. Fischer may have created the Vinland map to blunt the Nazi propaganda machine and to retaliate for the expropriation.

"The map shows two things clearly," she said. "The Roman Catholic Church was here first, long before Hitler and the Third Reich could claim any rights to the region, and it showed the Norse had discovered America long before Columbus. Whoever the Nazi authority was who was going to pronounce on such a map in the public eye would have to make a choice. Should the map be discarded because of its Catholic symbolism? Or should they go with the lovely idea of the Norse discovery of America?"

Anomalies in the map's legend—including its idiosyncratic account of Norse history—further implicate Fr. Fischer, Ms. Seaver says, who would have relied on inaccurate secondary sources. But her most tantalizing clue concerns a Czech library that may once have housed the Vinland Map parchment.

When Mr. Mellon purchased the map from a Connecticut rare books dealer in 1957, he also acquired two associated 15th-century works: The Tartar Relation and Speculum Historiale. The latter volume was incomplete, however, consisting of just the first four sections.

But in a Swiss auction catalog from 1934, Ms. Seaver found a listing for a manuscript fragment that appears to be the volume's missing fifth section. The catalog attributed the fragment to the Mikulov Castle library in Brno, a collection that was known for its antique maps and that Fr. Fischer consulted.

When the library was sold in the early 1930s, Ms. Seaver speculates, Fr. Fischer either bought or was given a bound edition containing both The Tartar Relation and Speculum Historiale, later converting some of the parchment—into the Vinland Map.

"If correct," said Peter Barber, head of map collections at the British Library, Fr. Fischer's connection to Speculum Historiale "is close to a smoking gun."

Close may be the best Ms. Seaver can do. Like her, Fr. Fischer was interested in map forgeries and even published an article on some Renaissance world maps that he suspected were fakes. And like her, he lacked a smoking gun.

"As far as I can see, none of these maps has an absolutely impossible appearance," he was obliged to concede.

"But all of them are to a greater or lesser degree strange and different from all other hitherto known maps."