She was kidnapped in September 2013, to the best of our knowledge. She was listed as being among American hostages held by ISIS but her name was withheld at the request of her parents which is why the media did not report her specific situation. After ISIS reported her death (convenient and “coincidental” with a Jordanian bombing), it was acknowledged she had been a captive. Likely she had been dead for many months after terrible torture.
According to Fox news, she was captured along with her Syrian boyfriend. The boyfriend was released, but he could not persuade the captors to release her.