Parents Confirm Identity of Islamic State Hostage After Militants Claim She Was Killed by Airstrike

The parents of the last known American hostage held by the Islamic State revealed their daughter's name publicly for the first time after the militant group claimed she was killed Friday by Jordanian-led airstrikes in northern Syria.

Claims that Kayla Mueller, a 26-year-old aid worker from Prescott, Arizona, was killed circulated Friday on IS-affiliated social media accounts, although no photographic evidence of her death has surfaced. IS published pictures of a damaged building, saying that Mueller was killed when Jordanian bombs hit the site.

Jordanian and American officials denied claims that Mueller was killed, stating that the announcement was likely a propaganda effort.

The White House National Security Council said in a statement that they were "deeply concerned" at the reports of her death, but have "not at this time seen any evidence that corroborates ISIL's claim."

Jordanian officials also rejected claims that Mueller had been killed. "What we know about this terrorist organization is that they are liars when it comes to these things," spokesman Mohammed al-Momani said.

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Mueller's parents confirmed her identity — which had been kept secret for fears of her safety — in a statement released Friday night. It has been widely known that IS had one last American female hostage, although details of her identity have remained unclear until now.

"This news leaves us concerned, yet, we are still hopeful that Kayla is alive," her family said. "We have sent you a private message and ask that you respond to us privately," added Carl and Marsha Mueller, pleading with their daughter's captors for her safe release.

Mueller was abducted in August 2013 by IS after leaving a facility run by the charity Doctors Without Borders (MSF) in Aleppo, Syria. Mueller was not employed by the aid group, but rather had accompanied a technician contracted by MSF to do repairs on the structure, according to a statement released Friday by MSF.

"On Aug. 3, 2013, a technician sent by a company contracted by MSF arrived at one of the organization's structures in Aleppo, Syria, to perform repairs. Unbeknown to the MSF team, Kayla, a friend of the technician's, was accompanying him. She was then abducted on the drive back," MSF said.

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ISIS American hostage Kayla Mueller and her mother Marsha (courtesy of the family) — Jim Acosta (@Acosta)February 6, 2015

Mueller had long been involved in humanitarian work, and had moved to Turkey in December 2012 to work with refugees from the Syrian war. "Kayla has devoted her life to serving others," Arizona Governor Doug Ducey said Friday.

"For as long as I live, I will not let this suffering be normal," said Mueller in a 2013 article for the Daily Courier. "[I will not let this be] something we just accept."

Last July, IS demanded a 5 million euro ransom in exchange for Mueller's release by August 13, 2014. The White House confirmed January 24 that they had been negotiating Mueller's release, but did not release details of her identity.

Claims of Mueller's killing come less than a week after IS announced they had killed a kidnapped Jordanian pilot in a gruesome video showing him being burned alive in a cage. In retaliation, Jordan has executed two al Qaeda prisoners and launched air strikes targeting the group.

Follow Olivia Becker on Twitter: @obecker928