BESIGHEIM, Germany - Barack Obama in German lederhosen? Researchers in the United States 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 Ancestry.com, Obama's sixth great-grandfather on his mother's side, 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, Pa., according to head genealogist Anastasia Tyler, who oversaw the research.

In Middletown, in Dauphin County, he married Anna Catherine Schockey in 1756 and had at least six children, including Ludwig Lewis Wolfley - Obama's fifth 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 to 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 told the AP. "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 to Wolfley relatively quickly. It wasn't until last Friday as a researcher pored over microfilmed documents at the Family History Library in Salt Lake City that they got the breakthrough documenting Wolfley's German ties, Tyler said.

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