He was 81.
Foster died Monday at the University of Virginia Medical Center in Charlottesville after a battle with prostate cancer and leukemia, the New York Times reported.
Nearly two centuries of gossip speculated that a relationship between Jefferson, the third president of the United States, and Hemings had resulted in the birth of at least one child. Foster and historian Winifred Bennett embarked on a mission in 1996 to use DNA testing to trace a possible link, the newspaper said.
Foster used a new genetic technique of tracing ancestry through the Y chromosome, which descends through the male line. He found that the Y chromosome of a descendant of Hemings' son, Eston, matched that of Jefferson's lineage.
The findings were published in 1998 in the journal Nature.
Putin thinks Obama would save him if he were drowning
Rosie O'Donnell unveils nearly 50-pound weight loss