File Photo: Abdul-Rahman Kassig, right, works as a medic to help a wounded man near Deir Ezzor Aug. 2013 (Photo: AP)
The parents of a US aid worker threatened with beheading by the Islamic State group say they've told their son's captors that they're unable to meet their demands.
Paula and Ed Kassig said during interviews broadcast Monday they've been doing all they can to free 26-year-old Abdul-Rahman Kassig since he was captured in Syria in October 2013.
Paula Kassig told NBC's "Today" show they received an audio recording of their son, formerly known as Peter, a couple weeks ago in which he said his time was running out.
A militant in an Oct. 3 video threatened Kassig's beheading in retaliation for US bombing attacks. Paula Kassig told "CBS This Morning" that the demands are beyond their power.