BESIGHEIM, Germany - Barack Obama in traditional German lederhosen? It may be hard to imagine, but U.S. researchers say they have located documents that prove the president has German roots dating to the 1700s.

According to parish records uncovered by experts at the genealogy Web site, Obama's sixth great-grandfather Johann Conrad Woelflin was born Jan. 29, 1729, in Besigheim, a small town north of Stuttgart on the Enz river where it feeds into the Neckar.

He sailed aboard a ship called "Patience" in 1750 to America, changing his last name to "Wolfley" upon arrival and eventually settling in Middletown, Pennsylvania, according to head genealogist Anastasia Tyler, who oversaw the research.

In Middletown, he married Anna Catherine Schockey in 1756 and had at least six children, including Ludwig Lewis Wolfley - Obama's 5th great grandfather - who was born in 1766, Tyler said.

The investigation was started by the Web site, which determined in 2007 that Obama had Irish ancestry, after researchers decided a few weeks ago it would be fun to try and prove or disprove rumored German ancestry ahead of the president's visit to Dresden today, Tyler said.

"We'd proved the Irish, so we just wanted to see if there was any truth to the rumors of German heritage," she said. "People supposed a few different lines that went to Germany, and the one that seemed the most plausible was this Wolfley line, so that's the one we concentrated on."

Tracing the ancestry of Obama's mother, Ann Dunham, the investigative team linked Obama back to Wolfley relatively quickly. But it wasn't until last Friday when a researcher was poring over microfilmed documents at the Family History Library in Salt Lake City, Utah, that they got the breakthrough documenting Wolfley's German ties, Tyler said.

Better than simple birth papers, the document - a so-called parish "Seelenregister" or "register of souls" - gave detailed information not only about Wolfley, but also his parents and grandparents.

"That was the absolute key piece to the puzzle," Tyler said. "Not only did it tie Johann Conrad back to Germany . . . but it gave us his parents names and these great details."

Among other things, the documents suggest Obama's family involvement in politics began centuries ago - the parish Seelenregister indicates Johann Conrad Woelflin's grandfather, Conrad Woelflin, was mayor for 30 years of Orsingen or Oefingen, both towns south of Stuttgart. The old script makes it difficult to read the name of the town exactly, but the Family History Library says a baptism record for one of Conrad Woelflin's sons lists Conrad as a "member of the court" in Oefingen, so that seems most likely. *