Prosecutors argued that Elsheikh was a member of an Islamic State terror cell that operated in Iraq and Syria, and whose members were nicknamed "The Beatles" for their British accents.

The cell caused outrage around the world after releasing videos of the executions of US journalists James Foley and Steven Sotloff.

US and British authorities say the IS Beatles were responsible for 27 killings in total, including British volunteers David Haines and Alan Henning and American aid workers Kayla Mueller and Peter Kassig.

The convictions in US District Court in Alexandria revolved around the deaths of four American hostages: Foley, Steven Sotloff, Peter Kassig and Kayla Mueller.

The jury deliberated for four hours before finding El Shafee Elsheikh guilty on all eight counts.

Who is El Shafee Elsheikh?

El Shafee Elsheikh came to the UK as a child refugee from Sudan and lived in White City, west London.

The 33-year-old former British national travelled to Syria in 2012 and joined al Qaeda before being radicalised by IS.

He was detained by US-backed Syrian Democratic Forces in January 2018 after the group's ringleader, Mohammed Emwazi, who was nicknamed Jihadi John, was killed in a drone strike.

Hostages assigned the members of the cell a name related to the members of the British band, The Beatles.

The men included Alexanda Kotey, who has already been jailed.

Aine Davis, in prison in Turkey, is not considered by the US Justice Department to be part of the cell.

Elsheikh is one of the most high-profile IS jihadists to face trial in the US, and his appearance in a federal court is the result of complex negotiations between America and the UK.

In 2018, his British citizenship was stripped from him.

Read more:
Who are the other Islamic State fighters nicknamed 'The Beatles'?

What did Elsheikh do?

Elsheikh has been found guilty of conspiracy to commit murder and lethal hostage-taking.

He was accused of taking a leading role in the kidnapping scheme that resulted in the deaths of four Americans: James Foley, Steven Sotloff, Kayla Mueller and Peter Kassig.

Court documents said that throughout the captivity of the US hostages and others, Elsheikh and Kotey supervised detention facilities holding the captives and were responsible for transferring them between facilities.

Mr Kassig, Mr Foley and Mr Sotloff were beheaded in videos that were then posted online and distributed around the world.

Ms Mueller was tortured and raped by Islamic State leader Abu Bakr al Baghdadi before being killed.

During the trial, Assistant US Attorney John Gibbs told jurors that Elsheikh "played a central role in a brutal hostage-taking scheme".

He has been described as the main guard in the group, with hostages saying he conducted most of the torture.

Read more:
ISIS terrorists dubbed the 'Beatles' admit mistreatment of US aid worker

'Utterly terrifying' - what we learned in opening statements

During opening statements, the court in Virginia heard how Elsheikh and his counterparts were "utterly terrifying" and held 26 Western hostages in a prison "called the desert".

Victims were subject to "unrelenting and unpredictable" abuse, prosecutors said, adding the perpetrators "seemed to enjoy beating" them.

They were given "dead legs" and placed in "stress positions" while being "threatened with murder", the court was told.

An example was given of one man, who was not named in the trial, who was beaten 25 times on his 25th birthday.

The defence did try to argue that Elsheikh could not be conclusively identified as a member of the terrorist cell, an argument that proved unsuccessful.

'Intense' beatings and being sent to 'the box' - hostage's testimony

Throughout the trial, a number of victims provided testimonies to the court - one of those was Italian aid worker Federico Motka.

He suffered 14 months of brutality at the hands of the IS Beatles - the longest of any hostage in the group - after being kidnapped near a refugee camp on the Turkish border in 2013.

The captors kept their faces covered, but prosecutors said they were distinguished through their preferences for punishment.

Mr Motka said Elsheikh "liked wrestling" and once put Mr Foley in a headlock so tight he passed out.

During the summer of 2013, Mr Motka explained that they were held in a location known as "the box", where he and others were subjected to a "regime of punishment" that included regular beatings and forced stress positions.

'Part of me is sure I'm going to die' - emotional letter from American hostage

As the trial entered its second week, jurors heard emotional testimony from the father of Peter Kassig, an aid worker who was executed by the terrorist cell after being taken hostage in 2013.

Ed Kassig took to the witness stand to read a heartbreaking letter written to him by his son while he was held captive.

"Dad, I'm paralysed here. I'm afraid to fight back. Part of me still has hope. Part of me is sure I'm going to die," it said.

Mr Kassig's long, handwritten letter was delivered to his family by a released hostage.

He wrote that his captors tried to tell him and the other hostages that they had been abandoned by their families and their countries for refusing to meet Islamic State's demands.

"But of course, we know you are doing everything you can and more. Don't worry Dad, if I do go down I won't go thinking anything but what I know to be true, that you and Mom love me more than the moon," it continued.

Even the judge, T S Ellis III, appeared to fight back tears as he called an early recess in the proceedings immediately after the testimony.

300 days of captivity - survivor describes meeting 'the Beatles'

French hostage Nicholas Henin was held captive for 300 days before being released in July 2014.

Within several days of being kidnapped, he said he managed to escape but was recaptured by ISIS fighters and taken to a police station.

Authorities swiftly returned him to his captors, who beat him, strung him up in the air dangling from handcuffs and then left him in a cell for 11 days with his wrists chained to his ankles.

He explained that he came across the Beatles in his later months in captivity. They were already recognised by other hostages as being particularly sadistic, he said.

He said the three Beatles would regularly inflict beatings, and that the Beatle they dubbed "Ringo" would frequently lecture the hostages on the justification for their captivity.