Alexanda Kotey, 38, pleaded guilty last September to eight criminal charges relating to the abduction, torture and beheading of IS hostages in Syria.
Kotey, originally from London, showed no emotion as judge Thomas Selby Ellis delivered his verdict.
Judge Ellis described his actions as “egregious, violent and inhumane”.
Of Kotey’s victims, the judge said: “These were not prisoners of war, these weren’t soldiers in the field…they were soldiers for good.”
The judge said Kotey “seems to have some remorse” and had offered to meet his victims’ families.
“If there is [an afterlife] maybe you can recompense there,” the judge said.
Who were the Islamic State ‘Beatles’?
Kotey declined an invitation to speak in court, saying he had nothing more to add to a letter he had sent to the judge before the sentencing.
Hostages said Kotey, El Shafee Elsheikh and Mohammed Emwazi were members of an IS cell they nicknamed “the Beatles” – after the band – because of their British accents. Emwazi was killed in Syria in 2015.
...........................................................A fourth man – Aine Davis – found guilty of being a senior member of a terrorist organisation and currently jailed in Turkey, is also believed to be part of the cell.
The group’s actions are said to have resulted in the deaths of four US hostages: journalists James Foley and Steven Sotloff and aid workers Kayla Mueller and Peter Kassig.
They are also blamed in the deaths of British aid workers David Haines and Alan Henning, and Japanese journalists Haruna Yukawa and Kenji Goto.
Kotey was captured by a Kurdish militia in Syria in January 2018 and handed over to US forces in Iraq, before being flown to the US in 2020 to face trial.
Elsheikh, 33, who was recently convicted of lethal hostage taking and conspiracy to commit murder, also appeared at the sentencing.
He is to be sentenced in August but Judge Ellis ordered him to be present at the hearing on Friday so statements need not be delivered twice by grieving families speaking in the Alexandria, Virginia courtroom.
Family members described the uncertainty they felt when their loved ones were in captivity, and the pain in the aftermath of their deaths.
On Friday morning, James Foley’s brother told the court he pitied the militants “for succumbing to hate”.
Michael Foley said his brother would want them to “spend the rest of their time in prison to reflect”.
Kotey wore a green jumper and looked directly at family members as they spoke.
Elsheikh sat quietly with his hands in his lap. At one point he closed his eyes, prompting Shirley Sotloff, Steven Sotloff’s mother, to say forcefully: “Please do not close your eyes. Look at me. You have to do that.”
David Haines’ daughter Bethany was among those who sat through every day of the Elsheikh trial.
In her statement, she said: “I haven’t had a good night’s sleep since before my dad was taken. I wake up during the night hearing my dad’s screams as he is being tortured by these men.”
She said grief has transformed her from “a popular and bubbly person with lots of friends” to somebody who shuts herself off from the world.
Ms Haines also asked to directly address the two defendants so that she could tell them they have lost both their family and their freedom and need to repent.
“No matter what you say this was not about religion. The only thing you can do that would help the victims would be to give up the location of the remains of our loved ones.”
David’s brother, Michael Haines, told them: “You inflicted more pain than I can ever put into words.”
But he said he refused to hold onto the anger he felt at the defendants, who he said had a hold on him and his family since the hostage-taking.
“For the first time, you have no power over me and mine,” he said. “I forgive you.”
Kotey and Elsheikh are the highest profile IS fighters to face justice in the US.
The two former Londoners were stripped of their British citizenship in 2018. As part of Kotey’s plea agreement, after 15 years the US government is required to make its best effort to move him to the UK – though he would still be required to serve the full life term.
