Sitting Bull (L), who died in 1890, and Ernie Lapointe, 73, a resident of Leed, South Dakota.

A lock of the hair of famous 19th-century Native American leader Sitting Bull has helped scientists confirm he was the great-great-grandfather of a South Dakota man, using a new method of family genealogy analysis with DNA samples from people who died long ago.

Researchers said DNA taken from the hair, which was preserved at the Smithsonian Institution in Washington, confirmed the family relationship between Sitting Bull, who died in 1890, and Ernie Lapointe, 73, a resident of Leed, South Dakota.

"I feel this DNA research is another way to confirm my great-grandfather's genealogy," said Lapointe, who has three sisters.

"People were questioning our ancestral relationship as far as I remember."

And this is the first time that DNA from a historical figure who died long ago has been used to show the link between them and a living individual, in a move that allows doing this with others using DNA from remains such as hair, teeth or bones.

19th-century Native American leader Sitting Bull.

The new method was developed by scientists led by Eske Willerslev, director of the Lundbeck Foundation's Center for Geographical Genetics at the University of Cambridge.

It took 14 years to find a way to extract usable DNA from hair, and the hair had rotted after being kept at room temperature before the Smithsonian handed it over to Lapointe and his sisters in 2007.

Willerslev said he had read in a magazine about the delivery of a lock of hair from Sitting Bull's scalp to La Pointe, and had contacted him.

"Lapointe asked me to extract DNA from it and match it with his own to prove the lineage," added Willerslev, the lead author of the research published in the journal Science Advances.

"I took a very small sample of hair and it contained very little DNA, and it took us to develop a way to during which they match the DNA of living people with a very small amount of ancient DNA over several generations, a long time.”

Sitting Bull, whose name in the local language was "Tatanka-Ayutanka," succeeded in assembling the "Sioux" tribes of the Great Plains against white settlers seizing tribal lands, and against the American army forces trying to expel the indigenous people from their land, and he led the Native American warriors who perished Federal forces led by George Custer at the Battle of Little Bighorn, which is now the US state of Montana.