A man described as the Islamic State's head of oil operations has been killed in a raid by US Marines.
US officials say Abu Sayyaf was killed during a raid by US commandos in eastern Syria sometime this weekend.
His wife has been captured alive.
It's believed she has key information about hostages the Islamic State has been holding.
Former CIA deputy director Michael Morell says documents discovered in the raid are also shedding light on potential plans the Islamic State may be considering.
"So, two documents in that cache. One is a document about how effective weapons of mass destruction can be against the enemy. That's us. One of those documents talks about how you actually make bubonic plague and how you use that against the enemy. That's us. And the other document talks about the religious justification for using weapons of mass destruction."
Abu Sayyaf has been described as the head of the Islamic State's oil operations, which has been key source of revenue for the group.
