Ryan tried to keep his presence in the region a secret, at least from the Sudanese government, for fear that it might seek to eliminate a witness. Once, a bombing seemed to target his hut, but he heard the plane approaching and ran out in his skivvies and took cover; the bombs missed, and he was unhurt.

After the first few weeks, the killings on the ground abated. But the government has continued the bombings.

“It’s terrifying when they bomb,” Ryan told me. “You don’t feel safe at any time of day or night.”

The bombs typically miss and have killed fewer than 200 people, he says, but they prevent people from farming their fields. Several hundred thousand people have been driven from their homes in the surrounding state of South Kordofan, Ryan says, and a famine may be looming.

“It’s not a good time to have kids,” Ryan quoted Jazira as telling him. “If we have kids, they’ll just starve.”

Frustrated by the lack of attention for the Nubans’ plight, Ryan decided to return to the United States this month and tell his story. He couldn’t get a visa for Jazira in time — obtaining an American visa for a spouse is a long and complex process — so she is in a refugee camp for 15,000 Nubans in South Sudan, struggling to address health needs there. Meanwhile, in Washington, Ryan has testified before Congress and met with White House officials.

Soon, he’ll go back, rejoining Jazira and sneaking back with her into the Nuba Mountains. It’ll be more dangerous than ever now that he has gone public, but he is determined to give voice to the voiceless — and Nubans will do everything to protect him.