The family of murdered journalist Steven Sotloff believe his location was sold to Islamic State (Isis) militants for up to $50,000 (£30,000) by a moderate rebel group in Syria.
Barak Barfi, a spokesman for and friend of Mr Sotloff’s family, said "sources on the ground" say a member of the group reached out to Isis and sold his location at the border crossing with Syria.
"Minutes before he was kidnapped, he called me from inside Syria to tell me that he was in," Mr Barfi told CNN.
"Somebody at the border crossing made a phone call to ISIS, and they set up a fake checkpoint with many people. Steve and his people that he went in with could not escape."
His whereabouts were sold for "something between" $25,000 and $50,000”.
"We believe that these so-called moderate rebels that people want our administration to support, one of them sold him probably for something between $25,000 and $50,000 to Isis, and that was the reason he was captured”.
Mr Sotloff was a freelancer who had contributed to magazines including Time, The Christian Science Monitorand Foreign Policy. He was kidnapped near Aleppo in August 2013 while trying to cross the Syrian border from Turkey.
Mr Barfi, a research fellow at the New America Foundation, described the relationship between the Obama administration and the family as “very strained” and said it "could have done more".
He also claimed “the administration made a number of inaccurate statements,” during the American journalist’s captivity and criticised the release of information about an unsuccessful rescue attempt in summer.
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies