An Iraqi soldier in Iraq’s Anbar province, where security forces cotninue to battle the Islamic State. AFP / AHMAD AL-RUBAYEAHMAD AL-RUBAYE/AFP/Getty Images

U.S. officials are questioning an Islamic State operative being held in American custody in Iraq regarding the group’s chemical weapons capability, U.S. and Iraqi officials said Wednesday.

U.S. Special Operations forces captured the operative, an Iraqi citizen, close to a month ago, a U.S. defense official said, speaking on condition of anonymity to discuss a sensitive operation. The man was captured by a Special Operations task force established by the Pentagon last year to intensify the U.S. fight against the militant group, which is arrayed across a wide area in Iraq and Syria.

The official said that interrogation of the prisoner, who is being held in an unspecified location in Iraq, was nearly complete. The man is expected to be transferred to Iraqi custody once the questioning concludes.

An Iraqi intelligence official, who also requested anonymity to discuss a covert operation, said the prisoner, Solaiman Dawood al-Afri, had worked in the military industry under former Iraqi leader Saddam Hussein and was related to another senior deputy to Islamic State leader Abu Bakr al-Baghdadi. The official said al-Afri was arrested in an “air drop operation” that included American elite Delta forces.

Afri is “one of the most important leaders in the organization, in charge of ISIS chemical weapons like chlorine and mustard gas,” the official said, using an acronym for the Islamic State. “He is in charge of many chemical attacks against the Iraqi forces and pesh merga,” the Kurdish security forces.

The Iraqi official said that Iraqi intelligence took part in questioning Afri and said he was being held under “joint authority.”

The prisoner is the second known Islamic State prisoner to be captured and questioned in Iraq by U.S. forces. Last year, U.S. officials held an Iraqi woman known as Umm Sayyaf, who was captured in a Special Operations raid in Syria, for several months before handing her over to the local authorities. She was later charged in a U.S. federal court.

Learning more from the new captive about the Islamic State’s chemical stockpiles or its plans to use such weapons would be a boon for the U.S. and Iraqi governments as they seek to prevent future attacks. Last spring, Iraqi Kurdish authorities claimed that Islamic State militants used chemical weapons in northern Iraq. U.S. officials believe the group has likely used mustard agents against its adversaries.

Adam Schiff, the top Democrat on the House Intelligence Committee, said that Afri’s capture was an illustration of why the Obama administration should be launching intensified operations against the Islamic State.

“While these on-the-ground captures pose real dangers to our troops and can risk bringing the U.S. more fully into this conflict, the rewards can be great in terms of vital intelligence collected, ISIS operations disrupted, and attacks thwarted – including those which may involve chemical weapons,” Schiff said in a statement.