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5 year oldMohamed Touré and his wife Denise Cros-Touré, both 58, were found guilty in January of bringing the young girl from Guinea to Texas and forcing her to work for them without pay in early 2000.
The couple, both citizens of Guinea, may lose their US immigration status, the US Department of Justice said.
Mr Touré is the son of Guinea's first president, Ahmed Sékou Touré.
The pair were also ordered to pay $288,620.24 (£222,702) in compensation.
The girl, who has not been named, is thought to have been five years old when she arrived in the US.
She was forced to clean, cook and take care of the couple's children for 16 years. They also confiscated her passport and denied her access to schooling.
According to a statement from the US Department of Justice, the girl was repeatedly hit, had her head shaved and forced to sleep alone in a nearby park as punishment.
In August 2016, she is said to have escaped from the couple's house in Southlake "with the help of several former neighbours", the justice department said.
Assistant Attorney General Eric Dreiband said: "The defendants stole her childhood and her labour for years, enriching themselves while leaving her with pain and an uncertain future."
Scott Palmer, a lawyer for Mrs Cros-Touré told the New York Times the couple planned to appeal the case claiming that the story was "wildly exaggerated".
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