The family of murdered journalist James Foley received an email from his captors last week which outlined their intention to execute him, GlobalPost's chief executive has confirmed.
Phil Balboni said the email was "full of rage against the United States for the bombing" of Islamic State targets.
"We communicated ... as quickly as we could with the captors and pleaded with them for mercy," he told reporters.
"[We] explained to them that Jim was an innocent journalist, had done no harm to the Syrian people ... Sadly they showed no mercy to Jim."
Foley was a freelance journalist working for the GlobalPost news site in Syria at the time of his capture in 2012.
A British family have told ITV News of their devastation after discovering a close relative is fighting with the Islamic State in Iraq.
A French journalist who was held hostage with James Foley in Syria has told ITV News it was "devastating" to see his murder.