The spymaster who oversaw the hunt for Islamic State’s most callous killers has warned that allowing two members of the evil ‘Beatles’ execution gang to stand trial in the West would be a ‘disaster of epic proportions’.

Alexanda Kotey and El Shafee Elsheikh are suspected of being part of the vile IS kidnap and execution cell led by Mohammed Emwazi, also known as Jihadi John, whose gruesome beheading videos appalled the world.

Emwazi was killed in a drone strike in November 2015, while Kotey, known by terrified captives as Ringo, and Elsheikh, who was nicknamed George, were captured by Kurdish forces in January 2018 and are locked up in northern Syria.

El Shafee el-Sheikh, left, and Alexanda Kotey, right, were captured by Syrian Democratic Forces. The pair were members of an ISIS cell led by Mohammed Emwazi - better known as Jihadi John. The group themselves were dubbed the ISIS Beatles

The British Government has stripped them of their citizenship and wants them extradited to America to face trial, but campaigners say they should face justice in British courts. However, in an interview with The Mail on Sunday, former CIA chief Douglas Wise warned that the pair would seek to turn the dock into a ‘pulpit’ from where they could ‘spew’ the murderous ideology of IS.

‘I think bringing them back to the United Kingdom would just be a disaster of epic proportions, if for no other reason than it would be a media spectacle,’ he said.

‘You’d have defence attorneys who would be making this a spectacle, the prosecution making it a media spectacle… it would just be horribly bad for Britain and particularly for the family members of the victims.’ Instead, Mr Wise believes that the pair, who were both raised in Britain, should be dealt with in Syria or Iraq, where they would face death by hanging if convicted.

‘Kurdish justice is a great judicial system when it comes to Arab extremists,’ Mr Wise said. ‘Or turn them over to the Iraqi government – they’ll hang them.’

The veteran spy chief, who spent 28 years with the CIA, also revealed extraordinary new details about the hunt for Emwazi.

He told how the extremist was betrayed by spies on the ground in Raqqa, IS’s de-facto capital in Syria, and praised the ‘extraordinarily courageous’ Syrians who were prepared to risk their lives to help Western intelligence agencies.

Mohammed Emwazi, better known as Jihadi John, was killed in a US drone strike. He and his cell are accused of abducting and beheading at least 27 western hostages

Intelligence experts confirmed the identity of Emwazi, who grew up in North London, and other key IS targets, before ordering deadly drone strikes by analysing the angle and texture of their beards, the veins on their necks and hands, the slope of their shoulders and the way they walked.

‘You want to make sure that you are actually going to smoke the right guy,’ said Mr Wise, who will appear tomorrow in The Hunt For Jihadi John, a Channel 4 and HBO documentary examining how Emwazi was hunted down and exterminated.

His views about the fate of Londoners Kotey, 35, and Elsheikh, 30, will raise new questions about what the UK should do with dozens of fighters and jihadi brides languishing in prison or camps following the fall of IS earlier this year.

The four-man ‘Beatles’ cell abducted and beheaded at least 27 Western hostages, including British aid workers David Haines and Alan Henning.

According to the US State Department, Kotey ‘likely engaged in the group’s executions and exceptionally cruel torture methods, including electronic shock and waterboarding’.

Elsheikh, who came to Britain as a child refugee from Sudan, ‘earned a reputation for waterboarding, mock executions and crucifixions’.

The fourth member of the cell, Aine Davis, was jailed in Turkey in 2017 after being convicted of being a senior IS operative.

Debate has raged over what the fate of the others should be.

A leaked letter from Home Secretary Sajid Javid to then US Attorney General Jeff Sessions exposed fears that UK laws may be inadequate to ensure a successful prosecution. Javid said that ‘a successful federal prosecution in the US is more likely’ and highlighted how America has charges for terrorism offences that are unavailable under UK law ‘and those offences carry long sentences’

Nicolas Henin, a French journalist who was one of the few captives to survive, tells the documentary that the pair should face a ‘fair trial’, adding: ‘We should not give them any chance to portray themselves as victims.’

But last year, a leaked letter from Home Secretary Sajid Javid to then US Attorney General Jeff Sessions exposed fears that UK laws may be inadequate to ensure a successful prosecution. Javid said that ‘a successful federal prosecution in the US is more likely’ and highlighted how America has charges for terrorism offences that are unavailable under UK law ‘and those offences carry long sentences’.

Some lawyers and human rights campaigners have demanded that the pair face justice in the UK. Speaking at the premiere of the documentary last week, Lord Anderson of Ipswich, a former independent reviewer of terrorism legislation, said the men should face trial, adding: ‘Why not in the UK?’

However, Mr Wise warned that there were too many ‘checks and balances’ in the UK justice system ‘for them to get the justice they so richly deserve’.

‘I think there’s a false anticipation of satisfaction if you brought them back to the UK and subjected them to the British judicial system,’ he said. ‘They need to be subject to some other process.’

Nicolas Henin, a French journalist who was one of the few captives to survive, tells the documentary that the pair should face a ‘fair trial’, adding: ‘We should not give them any chance to portray themselves as victims’

With his grey hair swept back into a 12 in ponytail, the 69-year-old admits that he is no James Bond as far as looks go. ‘My resemblance to Daniel Craig is slight,’ he jokes.

But Mr Wise is one of America’s most experienced intelligence officers, having been a CIA station chief four times, and he managed top-secret missions across the Middle East.

Married to a former FBI special agent, he was a member of one of the first CIA teams sent to Afghanistan after the 9/11 terror attacks on a mission to rout the Taliban and Al Qaeda. He later ran ‘The Farm’, the nickname for the CIA’s spy school in Virginia where agents are trained.

In August 2014, the father-of-three had just started a new job as Deputy Director of the Defense Intelligence Agency (DIA) in Washington when he was briefed about a horrific video in which an IS jihadi with a British accent was shown threatening America before beheading US hostage James Foley.

The video had been secretly obtained by the DIA and Mr Wise was warned that a gleeful IS would soon broadcast it online.

‘My first reaction on a human level was that this was heinous barbarism used for no other purpose other than propaganda pursuits,’ he said.

‘Nothing microscopically was accomplished by the beheading and the murder of various detainees.’

Despite attempts to mask his voice, Emwazi, who had been investigated by British police and security services for three years before he slipped off the radar in 2012, was identified by his London accent and the veins on his knife-wielding left hand.

Intelligence experts soon realised that the 27-year-old was not a senior member of the IS leadership. However, his acts of appalling brutality fuelled fears that his videos would become a potent recruitment tool – and propelled him up the US ‘kill list’ of jihadis to be targeted by air strikes.

‘He was a corporal. He was just a worker,’ said Mr Wise. ‘But ultimately… because of his eloquence, his baritone voice, his stature, the way he handled these murders, he became larger than life and thus added increased value to IS.

Jihadi John was killed in a suspected drone strike, although his fellow Beatles survived the war

‘This guy was the epitome of what an IS warrior represented, a powerful recruiting tool for these guys.’

Unlike senior members of Al Qaeda during the so-called war on terror, permission to kill Emwazi was not required from the US President, and the military and intelligence agencies were authorised to call in a drone strike the moment they were confident they had found their man.

‘He was a combatant, so therefore by definition he was subject to capital punishment in whatever way we decided to mete it out,’ Mr Wise said.

But the hunt was to involve more than a year of painstaking detective work.

While efforts to infiltrate IS had failed, Mr Wise said he believes that spies on the ground played a key role in ‘removing Emwazi from the battlefield’.

Even a snippet of seemingly innocuous information communicated electronically from inside Raqqa could help Western intelligence to locate him.

Mr Wise explained: ‘You could have one guy who says, “The left front tyre is bald.” Even if he didn’t tell you the colour or the type of vehicle, you just spend time focusing on the left front tyre.

‘It’s just one microscopic bit of information… but all of a sudden this one piece of information coalesces everything.’

Ultimately, it was Emwazi’s determination to visit his wife and child that allowed Western intelligence to fix his location.

The Hunt for Jihadi John will be on Channel 4 tomorrow night at 9pm

But they still needed confirmation that they had the right man before pulling the trigger. Mr Wise revealed that hours were spent poring over video footage, with analysts finding clues in the infrared and ultraviolet spectrum that are not visible to the naked eye.

‘The minute they [IS] produce a video, you have hundreds of thousands of frames of images which you can now painstakingly go through,’ he said.

‘You use these sort of cues like the angle of his beard, the texture of his beard, the vein structure on his neck and on his hands, how he cocks his head, his gait, the pace of his speech, all of this stuff you just pore over for hours and hours so you know what his emitted profile is.’

He said the team hunting Emwazi and other high-priority IS targets ‘wasn’t as big as you might believe’ and they were forced to juggle limited resources. It takes three drones working eight-hour shifts to follow just one jihadi for a day.

‘You can’t do that for 22,000 IS fighters and so you reserve the application of those resources to only those people who so richly deserve to die and whose death will have a material impact on the fight. Emwazi, very naturally, rose to high priority.’

On the evening of November 12, 2015, a drone followed Emwazi and other fighters as they travelled in a car towards Raqqa city centre. For 45 anxious minutes, the drone operators waited for an opportunity to strike.

In the documentary, Colonel Steve Warren, the US military spokesman in Iraq, says: ‘Sure enough, eventually he moves his vehicle into a relatively open area that in fact IS had used previously for executions. A sort of little poetic justice, I guess.’

Analysts checked the angle of Emwazi’s beard and the way that he walked and, satisfied that the long search was eventually over, ordered the missile strike.

Seconds later, a huge explosion confirmed the death of the executioner whose barbaric actions had transported the horrors of Iraq and Syria into living rooms in Britain.

Yet there were, said Mr Wise, no ‘high fives’ or ‘Hollywood, cork-popping moments’ among the spymasters who had overseen the hunt.

‘He was one of our own who had so dramatically and so precipitously turned his back on all of our core values,’ he said. ‘I thought it was just traitorous betrayal. He reflected everything that was the opposite of our core values of collective Americans and Brits.’

In the documentary, he speaks with brutal candour about how Emwazi’s instant obliteration contrasted with the prolonged and intense suffering of his victims. ‘You could argue that Emwazi’s departure, lethally and instantaneously, was perhaps unsatisfying.

‘It wasn’t a ten-minute execution. He didn’t have to feel the cut of the steel.’

Now there is another target: Abu Bakr al-Baghdadi, the IS leader.

Mr Wise believes his successors are in a race with Russia, Iran and Syrian forces to find and kill him. ‘We found Bin Laden, we are going to find this guy. We control more and more of the territory.

‘You are going to find that a number of our unnatural partners – who have no rules and there’s no human rights impediments to them – are going after him. His days are numbered.’