By Timothy R. Smith
Washington Post Staff Writer
Saturday, December 11, 2010; 5:23 PM
William Addams Reitwiesner discovered that presidents Warren G. Harding, Richard M. Nixon and Jimmy Carter were cousins; that the singer Madonna is related to Camilla Parker Bowles, consort to Prince Charles; that President Obama had ancestors who were slave owners; and that at least one U.S. senator was related to Elvis.
Mr. Reitwiesner (RITE-weez-ner), who held a series of low-paying jobs at the Library of Congress to be near the source of his research, spent almost all of his spare time devotedly cataloguing the pedigrees of U.S. political figures, European royals and celebrities.
Almost every day the library was open, he would do research in its genealogy reading room, working at a long wooden table as he single-mindedly entered data into a laptop computer.
"Some stay for 10 minutes," said one reference librarian in the genealogy reading room. "He stayed all day."
On Saturdays, Mr. Reitwiesner worked the entire day at the library. Weeknights, he would often stay until closing at 9 p.m. Then he would take his work home to his apartment on Capitol Hill, where he moved so he could always be close to the library.
"I work eight hours a day, sleep six and spend the rest of my time doing genealogical research," Mr. Reitwiesner told the New York Times in 1983.
He did it for fun, receiving no remuneration for his hours of work.
By culling books, newspaper clippings, census records and the occasional family Bible, he would chart the family trees of the influential and prominent in thorough detail.
Mr. Reitwiesner, who was 56 when he died Nov. 12 of complications from rectal cancer at the Washington Home hospice in the District, documented many of his findings on his Web site. He meticulously annotated where the information came from, such as slave shipment schedules, genealogical registers or baptismal reports.
During presidential election cycles, Mr. Reitwiesner traced the lineages of candidates, and his findings often made news. Former Sen. Fred Thompson, a Tennessee Republican, is related to Elvis, he found. Former president George H.W. Bush's family tree branched into three separate royal lines. In one connection, Mr. Reitwiesner said Bush and James A. Baker III, his secretary of state, were distant cousins.
"I've always been suspicious of far-out claims of kinship," Baker wrote in his 2006 memoir "Work Hard, Study . . . and Keep Out of Politics!," "and there's no way for me to judge the accuracy of Reitwiesner's work, other than to say that the bottom of his twelve-generation chart of my ancestry is consistent with Baker family records."
When investigating Obama's background, Mr. Reitwiesner found the future president's familial ties to a Virginia slaveholding family.
Mr. Reitwiesner was also an authority on continental European ancestry, especially Armenian and Syrian influences in the German noble houses.
His seven-volume "Matrilineal Descents of the European Royalty" has more than 5,500 pages of genealogies, including French and German royal lines. Some of the families he recorded went back to the turn of the first millennium.
William Addams Reitwiesner was born in Havre de Grace, Md., on March 8, 1954, and grew up in Aberdeen, Md., and Silver Spring.
He came to genealogy when he was 5. His grandfather, a board member of the National Genealogical Society, would conduct research in a narrow, book-filled study at his home in Covington, Va. On visits, William would explore the study, thumbing through the Encyclopaedia Britannica.
"I think it was a passion for facts," said Gary Roberts, a Boston-based genealogist who co-wrote "American Ancestors and Cousins of the Princess of Wales" (1984) with Mr. Reitwiesner.
Shortly after graduating from Silver Spring's Montgomery Blair High School in 1972, Mr. Reitwiesner joined the Library of Congress's Congressional Research Division as a cart pusher who fetched books for congressional offices and eventually became a computer technician.
He was on call during weekends, even though he was almost always at work - sequestered in the genealogy reading room, sifting through books.
Sometimes, Mr. Reitwiesner found that he was related to the subjects he was investigating. Take the case of Reubin Askew, who was governor of Florida in the 1970s. They were both descended from a British immigrant who settled in Virginia's Henrico County.
Mr. Reitwiesner always kept a card of his family tree tucked in his wallet.
He traced his direct family line back 14 generations to the late 16th century, listing more than 16,000 relatives.
One of Mr. Reitwiesner's distant ancestors was Edward I of England. Another ancestor was elected to Congress on the Know Nothing ticket, an American nativist political movement before the Civil War, and another branch of Mr. Reitwiesner's family came from Bavaria in the early 20th century.
Though consumed by genealogy, Mr. Reitwiesner had other interests, including contra dancing, a folk dance done in pairs. He was also an enthusiastic collector of T-shirts with risque slogans. He relished practical jokes, once rigging a card deck to deal royal flushes to each player. His snickering belied the prank.
Survivors include his mother, Hom McAllister Reitwiesner of Gaithersburg; three brothers, Andrew Reitwiesner of Ellenton, Fla., John Reitwiesner of Fredericksburg and Henry Reitwiesner of Colorado Springs, Colo.; a sister, Dorothy Reitwiesner of Gaithersburg; nieces and nephews; and countless distant cousins, many times removed.