Parents of Indiana aid worker Peter Kassig held by ISIS reveal letter

INDIANAPOLIS - An Indiana aid worker threatened with beheading by the Islamic State of Iraq and Syria said in a June letter that he's afraid to die and is saddened by the pain his captivity must be causing his family, his parents said Sunday.

In a statement released to media, Ed and Paula Kassig said their 26-year-old son, Peter Kassig, who changed his name to Abdul-Rahman while in captivity, thanked them for their strength and commitment. And he appeared to try to prepare them for his death.

"I am obviously pretty scared to die but the hardest part is not knowing, wondering, hoping, and wondering if I should even hope at all," Kassig said in the letter, according to his parents. "I am very sad that all this has happened and for what all of you back home are going through. If I do die, I figure that at least you and I can seek refuge and comfort in knowing that I went out as a result of trying to alleviate suffering and helping those in need."

Kassig was taken captive by the Islamic State of Iraq and Syria (ISIS, also known as ISIL) Oct. 1, 2013, in Syria, where he was providing aid for refugees fleeing that country's civil war.

The group said in a video after the beheading of British aid worker Alan Henning last week that Kassig would be next. The Kassigs pleaded for their son's freedom in a video statement released Saturday.

According to a former ISIS hostage, Kassig voluntarily converted to Islam sometime between his capture and December 2013, the Kassigs said.

The letter continues: "In terms of my faith, I pray every day and I am not angry about my situation in that sense. I am in a dogmatically complicated situation here, but I am at peace with my belief."

The Kassigs say the complication their son mentioned appears to arise from his conversion but that they see this "as part our son's long spiritual journey."

CBS News correspondent Holly Williams reports the Kassigs have begged the Islamic extremists for mercy.

In a family message, the Kassigs said: "Our hearts ache for you to be granted your freedom so we can hug you again and the set you free to continue the life you have chosen, the life of service to those greatest in need."

According to the family, Kassig is a former Army Ranger who formed the aid organization Special Emergency Response and Assistance, or SERA, in Turkey to provide aid and assistance to Syrian refugees. He began delivering food and medical supplies to Syrian refugee camps in 2012 and is also a trained medical assistant who provided trauma care to injured Syrian civilians and helped train 150 civilians in providing medical aid.