Ali went quiet. He looked away and his lip started to tremble. “The child’s body was mixed with the pieces of goat,” he said. “We didn’t know which piece was which.”

“The way he was killed was unbelievable,” he said, shaking with grief. The slaughter had convinced him that he must leave Somalia, and he asked for help getting into one of the Persian Gulf countries, where he had heard there was work. He wasn’t going back to his village. “There is no life there,” he said.

Our investigation in Somalia was the hardest reporting I’ve ever done, and I’ve been to Liberia during the Ebola crisis and Mosul after the defeat of the Islamic State. I don’t mean emotionally hard, as all wars are, or physically hard, since we were largely confined to a hotel in Mogadishu with heavily armed guards. I mean it was just hard to uncover the truth.

In most conflicts, we have access to a wealth of open-source evidence: online photos and videos, tweets and Facebook posts, on-the-ground reports from local media, huge bomb craters that appear on satellite imagery.

But in Somalia, we had almost none of that. The Shabab have banned internet-enabled mobile phones, so photos and videos of most attacks simply don’t exist; in our investigation over the past two years, we’ve found only 11 images. Virtually no one can send tweets with helpful dates from Shabab-held territory. And the United States is using lighter munitions — Hellfire missiles and other precision weapons with smaller warheads — that typically don’t produce craters we can see from space.

Fact-finding in war occurred before the age of smartphones, of course, but in Somalia, old-school methods fell flat, too. A trip to Shabab territory is an open invitation to be kidnapped, so I could not survey battlefields or dig through craters for scraps of bombs. The old flip phones that villagers are allowed to use are often monitored by American intelligence agencies and their Somali partners. Anytime we used words like “Al Shabab,” “bomb” and “drone,” they would have immediately been flagged by the algorithm in American surveillance devices. We couldn’t take the chance that innocent witnesses would inadvertently be pulled into the targeting program.

So we invited them to Mogadishu, asking them to travel along I.E.D.-infested roads and risk being accused by Shabab of being informants.