The two men helped supervise detention facilities where hostages were held, coordinated ransom negotiations for their release and engaged in a prolonged pattern of physical and psychological violence against their prisoners, charging documents said. For example, on April 25, 2014, prosecutors said, the men forced prisoners from Europe to witness the murder of a Syrian man by Mr. Emwazi as part of a hostage negotiation process.
“Emwazi executed the Syrian prisoner by shooting him in the back of the head and then numerous times in the torso as and when he fell into a grave,” the charging documents said. “Kotey instructed the hostages to kneel at the side of the grave and witness the execution while holding handmade signs pleading for their release. Elsheikh videotaped the execution of the Syrian hostage.”
It added: “After the execution, Kotey, Elsheikh, and Emwazi returned the European hostages to the prison with Elsheikh telling one hostage, “You’re next.”
All four men had lived in West London. Mr. Kotey, born in London, is of Ghanaian and Greek Cypriot background, while Mr. Elsheikh’s family fled Sudan in the 1990s. Both men have been designated foreign terrorists by the United States. The United Kingdom has stripped them of their British passports.
The Trump administration wanted to bring the two detainees to the United States for a trial in civilian court, as the families of their victims urged, but their transfer was delayed by a need for evidence in British hands that prosecutors viewed as essential to prove their case.
A lawsuit in Britain brought by the mother of one of the defendants tied up that government’s ability to share the evidence because the attorney general at the time, Jeff Sessions, refused to preclude seeking the death penalty, as normally happens in such cases since Britain has abolished it.
In August, however, Mr. Barr sought to resolve the impasse by reversing the policy and telling Britain that the United States would not seek to execute the two men. The British courts swiftly permitted the government to share the evidence — clearing the way for their transfer to American soil for the case to commence.