U.S. Captures Second ISIS Fighter. Now the Interrogation Begins.

The U.S. is holding and interrogating an Iraqi man suspected of fighting with ISIS in a growing effort to gather more on-the-ground intelligence about the Islamist terrorist group, two defense officials told The Daily Beast.

The detainee, who hasn’t been identified, is at least the second alleged Iraqi ISIS fighter captured and held by the U.S. since coalition airstrikes against ISIS began.

In May 2015, a raid on the Syrian compound of Abu Sayyaf, the nom de guerre for the ISIS operative who oversaw the group’s gas and oil operations, ended with his death and the capture of his wife, an Iraqi known as Umm Sayyaf. She was interrogated by U.S. authorities and provided valuable intelligence about ISIS’s inner workings, U.S. officials told The Daily Beast.

In fact, Umm Sayyaf yielded so much intelligence that her interrogations led to renewed efforts to conduct more interrogations rather than just depend on airstrikes to defeat the terror group.

The raid and subsequent interrogations yielded information that helped the U.S.-led coalition launch assaults on ISIS’s network of illicit oil sales, the first major assault on the heart of ISIS’s finances. Earlier this year, the coalition also struck three buildings in the Iraqi city of Mosul that housed an estimated $750 million of ISIS funds.

Officials said that the latest Iraqi prisoner is also being interrogated by U.S. authorities after being picked up by a U.S. expeditionary targeting force, which the U.S. military deployed to Iraq late last year to “put even more pressure” on ISIS, according to Secretary of Defense Ash Carter.

Umm Sayyaf was interrogated by a special unit called the High-Value Detainee Interrogation Group that gathers information primarily for intelligence purposes and not for criminal evidence to use in an indictment or at trial.

It’s not clear if the Iraqi man is also being interrogated by that group. But if his case is anything like Umm Sayyaf’s, he won’t be in U.S. custody for long.

Umm Sayyaf’s interrogation may have provided useful intelligence. But her case has proved to be a legal and diplomatic conundrum for the U.S.

Nine months ago, U.S. officials handed Umm Sayyaf to Iraqi Kurdish authorities for eventual prosecution. The U.S. said she’d face swift justice, likely for her role in imprisoning a pair of Yazidi women in her home, where they were sexually abused.

The move raised some eyebrows because Umm Sayyaf and her husband had also been holding prisoner a 26-year-old American aid worker named Kayla Mueller. U.S. officials said at the time that even if Umm Sayyaf weren’t prosecuted in connection with Mueller’s death while in ISIS custody, she would still be punished.

But the Kurds still haven’t filed charges against Umm Sayyaf for either Mueller’s death or the abuse of the Yazidi women.

Mark Alsalih, a Sunni lobbyist in Washington and the president of the Iraq Stability and Security Program who has close ties to Iraqi officials, told The Daily Beast that Iraqi Kurdish officials have said it’s up to the Americans what to do with Umm Sayyaf, and they’re waiting for direction.

For the Kurds, the case against Umm Sayyaf isn’t as simple as prosecuting the ISIS widow for the abuse of the two Yazidis. “The case also involves the death of Kayla Mueller,” Alsalih said.

The result is that both sides, the U.S. and the Kurdish Regional Government, seem to be pointing the finger at the other, unsure of what to do, and uncertain of what the other is willing to do.

The confusion helps explain why the Justice Department decided last month to file a criminal complaint against Umm Sayyaf for her part in an alleged conspiracy the resulted in Mueller’s death.

A U.S. official told The Daily Beast that the charges against her were more of an “insurance policy” in case Iraqi officials fail to charge her or she is ever transferred to another country or she escapes prison.

A criminal complaint is easier to obtain than an indictment and doesn’t mean that the U.S. will attempt to remove Umm Sayyaf from Iraqi custody. Indeed, at the time Umm Sayyaf was handed over to Iraqi authorities, a U.S. official told The Daily Beast that she couldn’t be extradited.

“We discussed the idea of her surrender and extradition to the U.S. with senior-level [government of Iraq] officials, but ultimately that option was not available as Iraq has a constitutional prohibition on surrendering Iraqi citizens to foreign authorities,” the official said.

It’s not clear what charges the Kurds might file against the Iraqi man now in custody. But if Umm Sayyaf’s case is any guide, there may be confusion over what to do with him, too.