London, Asharq Al-Awsat—In exclusive comments to Asharq Al-Awsat US lawyer Stanley Cohen spoke of his “extraordinary anger” on hearing of the brutal execution of American aid worker Peter Kassig by the Islamic State of Iraq and Syria (ISIS), ending six weeks of frenetic efforts to save his life.

As revelations emerged about the failed attempt to save Peter Kassig, the American aid worker who embraced Islam during his one year in captivity and who was killed by ISIS on November 16, Asharq Al-Awsat spoke to Stanley Cohen, the controversial US lawyer who masterminded the back-channel talks about how and why his efforts ultimately failed. Cohen is a well-known American Jewish lawyer with a long history of representing controversial figures, including Osama Bin Laden’s son-in-law Sulaiman Abu Ghaith and various members of Hamas in US courts.

Britain’s Guardian newspaper first broke the story of the US-backed talks between jihadist clerics and ISIS leadership to secure Kassig’s release, and the story was published today in full in the Arabic edition of Asharq Al-Awsat newspaper in cooperation with the Guardian.

The talks saw prominent non-ISIS jihadist scholars, including Abu Qatada and Abu Muhammad Al-Maqdisi, open a dialogue with ISIS chief “scholar at arms” Turki Bin Ali not just over the fate of Kassig, but over the group’s policy of capturing and executing journalists, aid workers and civilians, and other juristic differences of opinion between ISIS and other jihadist organizations, including Al-Qaeda and Al-Nusra Front.

“We had a collection of former Gitmo prisoners, we had doctors and lawyers and sheikhs from Kuwait. We had active members of Al-Qaeda. We had active members of Al-Nusra. And we had Sheikh Maqdisi and Sheikh Qatada,” Cohen told Asharq Al-Awsat.

“It was all I did for six weeks. It was extraordinarily tense and difficult and complicated especially since it was essentially secret except for the people involved,” he added, speaking of the weeks of travel and talks, visiting Kuwait and Jordan to try to bring both sides to agreement.

While securing Kassig’s release was Cohen’s primary concern, the talks between the jihadist scholars and Bin Ali expanded to include ways to tone down the inter-jihadist conflict that has been raging over the group’s brutal tactics in Iraq and Syria, and would see each side stop denouncing the other as apostates and infidels and ISIS agree to stop taking hostages altogether, according to the Guardian report.

“It wasn’t just about Peter Kassig it was an effort underway by a group of people, mostly Muslims, very political, senior religious figures and former fighters, to ratchet down the violence levels particularly related to civilians,” Cohen told Asharq Al-Awsat.

However the weeks of effort and pressure ultimately failed at the final hurdle after the Jordanian intelligence services arrested Maqdisi on charges of “using the Internet to promote and incite views of jihadist terrorist organizations,” contravening a “negotiations protocol” that Cohen had put together—with the assurances of the FBI—that Maqdisi, Abu Qatada and others would not be monitored or arrested for contacting ISIS.

“The arrest of Muhammad Al-Maqdisi basically guaranteed the negotiations would fail. It killed it,” Cohen said.