As two ISIS militants faced a judge in Virginia, Diane Foley listened from home through a muffled phone connection. She strained to make out the voices of the men that prosecutors say kidnapped her son before he was murdered.
Alexanda Kotey and El Shafee Elsheikh are accused of belonging to an ISIS cell known as "the Beatles", an incongruously lighthearted nickname for four Britons blamed for the jailing, torture and murder of western hostages in Syria.
After geopolitical breakthroughs and stalemates, military action in Syria and court fights in London, the US Justice Department's most significant terrorism prosecution in years got under way at last in October.
For Ms Foley, who months earlier pleaded with Attorney General William Barr to secure justice by forswearing the death penalty, it felt miraculous that the case was happening at all.
“We’d met so many blocks over the years, I couldn’t believe it was happening,” she said.
“I was in awe of it, really, and almost didn’t trust it. Is this really happening?”
The prosecution is a counter-terrorism success in the waning months of the Trump administration. But it almost did not 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 UK, 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 Mr Barr to do the same enabled the US to obtain crucial evidence it needed.
“There was never a time when I thought we didn’t have any case,” said John Demers, assistant attorney general for national security.
“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 ISIS barbarism with the 2014 release of grisly propaganda videos depicting the beheadings of American hostages.
The first showed James Foley, who was 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.
An air strike subsequently killed that man, known as Jihadi John, the group's most notorious member. Another member was prosecuted in Turkey.
Kotey and Elsheikh were captured in Syria in 2018 by US-backed Syrian forces.
Officials at the Justice Department weighed up whether the men should be tried in the UK or US, or even transferred to the US military prison at Guantanamo Bay in Cuba.
US authorities initially leaned towards a UK prosecution. Britain accumulated compelling evidence and US policy encouraged other nations to repatriate and prosecute their citizens who joined ISIS.
But the UK, which stripped the men of their citizenship, resisted hosting the trial, in part over concerns about the ability to obtain convictions and issue significant prison terms.
British authorities also imposed a condition on any prosecution the US might bring, refusing to share evidence without assurances the US would not seek the death penalty, which has long been abolished in the UK.
But US officials considered such evidence vital.
The UK relented eventually, agreeing to share evidence without the assurances. But Elsheikh's mother sued and, last March, a British court effectively blocked the sharing of evidence.
Despite the ruling, prosecutors pressed forward. George Zachary Terwilliger, US attorney for the Eastern District of Virginia, whose office is handling the prosecution, argued internally that getting the men to the US was more important than leaving the death penalty on the table.
The families also began to unite around the idea of removing the death penalty from consideration. That was notable because they had not always held the same views.
The executions of Foley and two other hostages, Steven Sotloff and Peter Kassig, were shown in propaganda videos.
But the circumstances of the death of a fourth, Kayla Mueller, who prosecutors claim was sexually abused by Abu Bakr Al Baghdadi, leader of ISIS at the time, were less clear.
Her parents initially believed keeping the death penalty on the table could provide leverage to obtain answers.
Ms Mueller's mother, Marsha, said in a text message that the couple simply wanted information.
Ultimately, though, when it came to the death penalty: “The other families who we care so deeply for wanted the men brought here and this seemed to be the only way they would come.”
Current and former FBI officials who had been advising the families encouraged them to speak out to prod the Trump administration into action.
Ali Soufan, a former FBI counter-terrorism agent, told them that the straightest path to justice involved waiving the death penalty.
Other options were hardly optimal. The likelihood of a legitimate trial in Iraq, where the men were being held by the US military, was uncertain. Holding proceedings there would risk a human rights outcry.
In the summer, as the families made clear their wishes to remove the death penalty from consideration and as the case dragged on without an obvious resolution, Mr Barr agreed to break the deadlock.
On August 18, he vowed in a letter to UK Home Secretary Priti Patel that the US government would forgo the death penalty.
He said that if the Justice Department received the evidence by October 15, it would proceed with prosecution. If not, the US would transfer the men to Iraqi custody.
The evidence came, resulting in a 24-page indictment with terrorism counts punishable by life in prison.