It was the feel-good news story of the season: on Christmas Eve, one of Argentina's best-known rights activists, 92-year-old Maria "Chicha" Mariani, announced she had finally located her lost granddaughter, who was abducted as a 3-month-old baby during the country's 1976-1983 military dictatorship.

Even Argentina's president, Mauricio Macri, congratulated her on Twitter, wishing Mariani, "her granddaughter and her whole family, a happy Christmas reunion."

However, Sunday, Mariani announced that further DNA testing proved she had been reunited with the wrong woman, reported the BBC. The results of at least two DNA tests have been made public, which "are conclusive in showing that there is no relationship between the genetic profile of this young woman and the Chicha Mariani family group," stated Pablo Parenti, chief of the government's Special Unit for Cases of Child Kidnapping.

As a founder of Grandmothers of the Plaza del Mayo, a human rights collective working to locate children who were stolen or illegally adopted during Argentina's military regime, Mariani has spent almost 40 years searching for her lost granddaughter, Clara Anahi Mariani, according to the Independent.

There has been no indication that the woman who met Mariani was trying to deceive her, explained the Journal. The activist conveyed that she remains hopeful and will continue to search her granddaughter, according to the BBC. Mariani's organization has already reunited 119 children with their families.

An estimated 500 children were abducted during Argentina's dictatorship, according to the Guardian. Most of the children were given to military families, to be raised as law-abiding citizens loyal to the regime.