Kayla Jean Mueller, the U.S. aid worker whose death as a captive of Islamic State extremists was confirmed Tuesday, was among the hostages sought in a failed U.S. rescue attempt last year, President Barack Obama said.

Obama, in an interview on Tuesday with the web site BuzzFeed, confirmed for the first time publicly that Mueller was in the group that included journalist James Foley which U.S. special operations forces tried to rescue in northern Syria last August, only to discover they had been moved.

The raid was initially disclosed by the White House after Islamic State on Aug. 19 released a video of Foley's beheading.