El Shafee Elsheikh, who was formally sentenced to life in prison Friday for a leading role in the beheading deaths of American hostages, had a somewhat whimsical nickname as a so-called "Beatle" that belied the viciousness of his conduct.

In fact, he is the most notorious and highest-ranking member of the Islamic State group to ever be convicted in a U.S. court, prosecutors said at his sentencing hearing in U.S. District Court in Alexandria.

Elsheikh and British counterparts Alexanda Kotey and Mohammed Emwazi led an Islamic State hostage-taking scheme that took roughly two dozen Westerners captive a decade ago. The hostages dubbed them Beatles because of their accents. Their appearance, always in masks, invoked dread among the hostages for the sadism they displayed.

"This prosecution unmasked the barbaric and sadistic ISIS Beatles," said First Assistant U.S. Attorney Raj Parekh.

The life sentence was a foregone conclusion after a jury convicted him of hostage taking resulting in death and other crimes earlier this year.

The convictions carried a mandatory life sentence. The U.S. agreed not to pursue a death sentence as part of a deal that ensured extradition of Elsheikh and his friend, Kotey, who has already been sentenced to life. Emwazi was killed in a drone strike.

The convictions revolved around the deaths of four American hostages: James Foley, Steven Sotloff,Peter Kassig, and Kayla Mueller. All but Mueller were executed in videotaped beheadings circulated online. Mueller was forced into slavery and raped multiple times by Islamic State leader Abu Bakr al-Baghdadi before she was killed.

They were among 26 hostages taken captive between 2012 and 2015, when the Islamic State group controlled large swaths of Iraq and Syria.

Parekh said it was difficult to convey the brutality of Elsheikh's actions. "We lack the vocabulary of such pain," he said, paraphrasing Dante's Inferno.

Still, victims of Elsheikh and the Beatles testified at Friday's hearing and gave voice to what they experienced. Danish photographer Daniel Rye Ottosen, who was released after a ransom was paid, said the worst moments were times of silence during and after captivity when he was alone with his thoughts.

He said when Elsheikh and the Beatles beat him up, it was almost a relief.

"I knew I could only concentrate on my pain, which is much easier than being alone with your thoughts," he said.

Ottosen was particularly close to Foley, and memorized a goodbye letter that Foley wrote to his family so he could dictate it to Foley's parents when he was released.

Foley's mother, Diane Foley, said holding Elsheikh accountable at trial sends a message of deterrence to other would-be hostage takers.

"Hatred truly overwhelmed your humanity," she told Elsheikh on Friday, which was the eighth anniversary of James Foley's beheading.

At trial, surviving hostages testified that they dreaded the Beatles' appearance at the various prisons to which they were constantly shuttled and relocated. Elsheikh and the other Beatles played a key role in the hostage negotiations, getting hostages to email their families with demands for payments.

They also routinely beat and tortured the hostages, forcing them to fight each other to the point of passing out, threatening them with waterboarding and forcing them view images of slain hostages.

Elsheikh, 34, did not speak during Friday's hearing. His lawyer, Zachary Deubler, said Elsheikh will appeal his conviction. Elsheikh's lawyers had argued that his confessions should have been ruled inadmissible because of alleged mistreatment after he was captured by Kurdish-led Syrian Defense Forces in 2018.

At Friday's hearing, Deubler confined his arguments to a request that Elsheikh not be sent to the supermax prison facility in Florence, Colorado, where he would face solitary confinement for the rest of his life. Deubler said a designation to Florence is almost a certainty unless the judge recommends otherwise.

Judge T.S. Ellis III declined to make any recommendation to the Bureau of Prisons.

"The behavior of this defendant and his co-defendant can only be described as horrific, barbaric, brutal, callous and, of course, criminal," Ellis said.

Outside court, Mueller's parents said they are still seeking information about her death and to recover her remains. Carl Mueller said he could not help but reflect on the disparate outcomes for European hostages - who were released after ransoms were paid - and American hostages who were killed because the U.S. refuses to pay ransom.

"Hopefully our government in the future will do like so many others do, and get them home, not leave them," he said.

The Muellers and Diane Foley both said they have been able to meet with Kotey, whose guilty plea requires him to meet with interested families. Marsha Mueller declined to comment on her conversation.

Dian Foley said she met with Kotey three different times, and it was beneficial to her.

"I was able to share some of who Jim was and he was able to share some of why he felt it was a war situation and his excuses," Foley said. "But he did articulate some remorse and and I was grateful for that."

From The Associated Press