Richard Engel has been NBC News' chief foreign correspondent since 2008.
"His relatives were subjected to harsh treatment by ISIS and he no longer believed in the future of ISIS. He wanted to take revenge on ISIS and al-Baghdadi himself," Gen. Mazloum Abdi told NBC News.
The informant proved to U.S. intelligence that he had direct access to Baghdadi this summer by turning over the ISIS leader's used underwear and a sample of his blood.
U.S. forces have been pulling out of northern Syria amid growing chaos after Turkey invaded the region earlier this month.
"I want him to stay committed to his words," the head of the Kurdish-led Syrian Democratic Forces said of President Donald Trump.
Many of the prisoners who spoke to NBC News appeared to know little of the chaos that was unfolding around them beyond the confines of their compound.
Yuriy Lutsenko said he was friends with the president's personal attorney and that the pair had known each other for "many years."
Six months ago ISIS lost all of its territory and tens of thousands of fighters in Iraq and Syria — but it lives on.
One Icelandic glacier is receding annually by the length of an Olympic swimming pool. This is what scientists are doing about it.
Clemson University researchers found videos of confrontations between white people and minorities received instrumental early social media promotion from inauthentic accounts.
A deal with the Taliban would open the way for Afghan peace talks with insurgents. But skeptics say a hasty U.S. exit could tip the country into chaos.