“If you take away that funding and pressure, it is not sustainable,” said Heather Barr, Afghanistan researcher for Human Rights Watch.

As more details of Sahar Gul’s case have come to light — including the fact that the abuse continued even as, time and again, neighbors, police officers and her family members voiced suspicions that something was wrong — it has only reinforced how vulnerable women and girls still are in Afghanistan, particularly in rural areas where under-age marriages are common and forced ones are typical.

Sahar Gul, who is now about 14, grew up in Badakhshan, a poor, mountainous province in the north. As a young child she was shuffled around after her father died, ending up with her stepbrother, Mohammad, when she was about 9. She helped with the hard work — tending cows, sheep and an orchard of walnut and apricot trees, and making dung bricks for the fire — but her stepbrother’s wife resented her presence. The woman pressured Mohammad to give Sahar Gul up for marriage after he was contacted by a man, about 30, named Ghulam Sakhi — even though she had not yet reached the legal marriage age of 16, or 15 with a father’s consent.

In effect, Ghulam Sakhi bought her: he paid at least $5,000, according to government officials and prosecutors, an illegal exchange. He drove off with Sahar Gul to his parents’ home in Baghlan, another northern province hundreds of miles away.

Ghulam Sakhi’s first wife had fled after he and his mother beat her for not bearing children, according to Rahima Zarifi, the chairwoman of Baghlan’s women’s affairs department, and the mullah in the mosque in the town in Baghlan. In his search for a new wife, there may have been a reason Ghulam Sakhi’s family looked so far afield: they intended to force her into prostitution, according to Ms. Zarifi, who followed the case closely, and officials at the Ministry of Women’s Affairs in Kabul.