Islamic State of Levant (ISIL), formerly known as ISIS, has released a statement claiming that U.S. female aid worker Kayla Jean Mueller was purportedly killed in the Jordanian airstrike that took place after the militants released a video showing brutal execution of Jordanian pilot, according to terrorism watchdog SITE Intel. The claim is being investigated by the CIA.

In August 2014, ISIS had demanded a ransom of $6.6 million for her. She was being held in Syria. Mueller was captured there in August 2013 with a group of other aid workers, who have since been released.

According to The Daily Courier, Mueller grew up in Prescott, Arizona, and her parents are Carl and Marsha Mueller. She attended Northern Arizona University in 2007, when she expressed her interest in Darfur crisis to the paper, "I love cultures and language and learning about people's cultures."

Mueller worked for the group Support to Life in Turkey, which offers support and relief to refugees from the Syrian Civil War, the Courier reported.

After ISIS released the video of the burning execution of Jordanian pilot Muath al-Kasasbeh, Jordan increased their bomb attacks in ISIS strongholds.

According to Site Intel, the Islamic State released photos of the destroyed building in which Mueller was located in Syria's ar-Raqqah governorate.

ISIS had lied about hostage deaths, including the Jordanian pilot, whose execution video was dated from early January, but claimed that he was still alive during the demand to exchange him for failed suicide bomer, Sajida al-Rishawi, in late January. However, until the claim has been confirmed, there is little hope of Mueller's survival.

American officials said they were looking into the report, according to The Associated Press.

Mueller is an American aid worker whose identity was never disclosed out of concerns for her safety. If her death is confirmed, she would be the fourth American to die under the captivity of Islamic State militants. Other Americans who were beheaded were journalists James Foley and Steven Sotloff and aid worker Peter Kassig.

The Jordanian government has not released any comments on whether its planes had struck Raqqa on Friday.