As two Islamic State militants faced a judge in Virginia last month, Diane Foley listened from home through a muffled phone connection and strained to make out the voices of the men prosecutors say kidnapped her son before he was murdered. Alexanda Kotey and El Shafee Elsheikh stand accused of belonging to an IS cell dubbed “the Beatles,” an incongruously lighthearted nickname for British citizens blamed for the jailing, torture and murder of Western hostages in Syria. After geopolitical breakthroughs and stalemates, military actions in Syria and court fights in London, the Justice Department´s most significant terrorism prosecution in years was finally underway. For Foley, who months earlier had pleaded with Attorney General William Barr to pursue justice by forswearing the death penalty, the fact the case was proceeding at all felt miraculous. “We’d met so many blocks over the years, I couldn’t believe it was happening,” Foley said. “I was in awe of it, really, and almost didn´t trust it – a bit incredulous. Is this really happening?” The prosecution is a counterterrorism success in the waning weeks of the Trump administration. But it almost didn’t happen. Interviews with 11 people connected to the case make clear the hurdles along the way, including a death penalty dispute that required two normally close allies, the US and U.K., to navigate fundamental differences in criminal justice systems. In the end, the interviews show, grieving families reached a gradual consensus to take capital punishment off the table while a key commitment by Barr to do the same enabled the US to obtain crucial evidence it needed. At another time, the case might not have even been handled in civilian courts. After the Sept. 11 attacks, the Republican-led Justice Department favored detaining foreign fighters at the US base in Guantanamo Bay, Cuba, for military tribunals. But that approach changed. Now federal prosecutors are pursuing the highest-profile terrorism case since trials over the Boston Marathon bombing and Benghazi attack, aiming to secure convictions and punishments that can keep the men, in their 30s, imprisoned for life. “There was never a time when I thought we didn’t have any case,” said John Demers, assistant attorney general for national security. But, “we didn’t want to bring them here unless we had really good charges, a really strong case, and ultimately expected a conviction that was going to result in a very significant prison sentence.” The group of militants, called “the Beatles” by their captives because of their British accents, came to embody IS barbarism with the 2014 release of grisly propaganda videos depicting the beheadings of American hostages. The first showed James Foley, captured as a freelance journalist covering Syria’s civil war, kneeling in the desert in an orange jumpsuit beside a masked man in black brandishing a knife to his throat. The beheadings were part of a reign of terror that officials say also involved waterboarding, mock executions and electric shocks. Elsheikh once videotaoed the shooting of a Syrian hostage as Kotey directed hostages to watch while holding signs pleading for their release, prosecutors say. The pair also coordinated ransom demands, the indictment says. An email to the Foleys tauntingly told them the US government treated them “like worthless insects.” An airstrike killed the group’s most notorious member, who had killed Foley and was known by the moniker of “Jihadi John.” Another was prosecuted in Turkey. That left Kotey and Elsheikh, who were captured in Syria in 2018 by American-backed forces. Weeks later, they appeared unapologetic while speaking to The Associated Press at a Kurdish security center, denouncing the US and Britain as hypocrites who wouldn’t give them a fair trial.Inside the Justice Department, officials weighed whether the men should be tried in the U.K. or US or even transferred to Guantanamo, which then-Attorney General Jeff Sessions had called a “very fine place” even though prosecutions there have floundered, lagging behind the speedier justice of American courts. US officials initially leaned toward a U.K. prosecution. British authorities had accumulated compelling evidence during their own investigation and US policy encouraged other nations to repatriate and prosecute their citizens who’d joined IS. Yet the U.K., which had stripped the men of their British citizenship, resisted doing the case in part over concerns about the ability to get convictions and significant prison sentences in British courts. Once that position became clear, officials coalesced around bringing the men to America, said State Department counterterrorism coordinator Nathan Sales. But the British balked at sharing evidence with US prosecutors without assurances they wouldn’t impose the death penalty, which was abolished in the U.K. That was an impediment for American officials, who say they considered Britain’s evidence vital in tracing the men’s travel and path of radicalization.