By the summer of 2011, Captain Quinn and Sergeant Martland, both Green Berets on their second tour in northern Kunduz Province, began to receive dire complaints about the Afghan Local Police units they were training and supporting.

First, they were told, one of the militia commanders raped a 14- or 15-year-old girl whom he had spotted working in the fields. Captain Quinn informed the provincial police chief, who soon levied punishment. “He got one day in jail, and then she was forced to marry him,” Mr. Quinn said.

When he asked a superior officer what more he could do, he was told that he had done well to bring it up with local officials but that there was nothing else to be done. “We’re being praised for doing the right thing, and a guy just got away with raping a 14-year-old girl,” Mr. Quinn said.

Village elders grew more upset at the predatory behavior of American-backed commanders. After each case, Captain Quinn would gather the Afghan commanders and lecture them on human rights.

Soon another commander absconded with his men’s wages. Mr. Quinn said he later heard that the commander had spent the money on dancing boys. Another commander murdered his 12-year-old daughter in a so-called honor killing for having kissed a boy. “There were no repercussions,” Mr. Quinn recalled.

In September 2011, an Afghan woman, visibly bruised, showed up at an American base with her son, who was limping. One of the Afghan police commanders in the area, Abdul Rahman, had abducted the boy and forced him to become a sex slave, chained to his bed, the woman explained. When she sought her son’s return, she herself was beaten. Her son had eventually been released, but she was afraid it would happen again, she told the Americans on the base.

She explained that because “her son was such a good-looking kid, he was a status symbol” coveted by local commanders, recalled Mr. Quinn, who did not speak to the woman directly but was told about her visit when he returned to the base from a mission later that day.