Video report by ITV News Security Editor Rohit Kachroo
A Briton believed to be part of Jihadi John's infamous beheading gang is on trial in Turkey over a new IS terror plot in the country, secret court papers uncovered by ITV News have revealed.
Aine Davis, 32, was one of four British suspects, dubbed the IS "Beatles", arrested last November in Istanbul.
The London-born former gangster was named by ITV News in February as one of the "Beatles" - who held foreigners hostage in Syria before killing them on film.
He crossed the border from the terror network’s stronghold of Raqqa last year and was detained by anti-terror police on November 12 2015 - the day before co-ordinated IS terror strikes in Paris.
Turkish officials have never released details of the charges against Davis and his alleged accomplices, and their trial is due to start in secret next month.
But ITV News has obtained full details of the allegations against the group – as well as Davis’ denial that he was ever involved.
The documents represent the prosecution against the most senior British alleged IS fanatic happening anywhere in the world.
Prosecutors claim Davis is "considered to be in charge of Daesh (also known as IS)" and accuse him of slipping back into Turkey to plan a new act of terrorism.
But Davis told Turkish terror police he travelled to Syria to simply deliver aid before leaving because of "the wrongdoings that were going on", according to the papers.
Details of the charges against Davis come as he was revealed to have been part of a gang of IS prison guards that included Mohammed Emwazi - known as 'Jihadi John'.
The two men had been friends in west London before travelling to Syria within months of each other.
They were joined by a third friend, 32-year old Alexe Kotey, who had played a role in their radicalisation on the streets of Ladbroke Grove.
ITV News has established that together they formed a group of IS hostage-takers known by their victims as "The Beatles" because of their distinctive British accents.
But the 14-page Turkish prosecution document reveals that Davis told counter-terrorism officers "that the person known as Jihadi John was not his friend; that he only used to pray in the same mosque with him (in London); that they had not seen each other for a long time".
Davis also directly dismissed claims that he was a member of "The Beatles" - telling detectives "that the news in the media was baseless; that the news, which portrayed him as being in charge of the prison where hostages were kept did not reflect the truth".
Davis stands accused of smuggling himself from Syria into Turkey by using the codename Ebu Eyyup El Britani and with the help of a high-ranking IS border commander.
He travelled to Istanbul "for a short and important meeting" to plot a major terrorist attack, prosecutors allege. But shortly after arriving in the city last November, he was arrested.
The former Tube driver came to attention in 2014 when his wife, Amal El-Wahabi, became the first person in Britain to be convicted of funding jihadis in Syria.
She was jailed for hoodwinking an old school-friend into agreeing to take 20,000 Euros to Turkey for her husband.
During his interrogation by Turkish police last year, officers confronted Davis with a Daily Telegraph article published online at the time of his wife’s conviction.
Under the headline ‘British jihadist at the heart of terrorist network in Syria and Iraq’, he is pictured inside Syria.
Asked whether the image was proof of his role within the terrorist organisation, he told detectives that it was taken in Idlib before the city was seized by IS.
According to the secret files, which ITV News has translated into English, he claimed he was photographed “only for the purpose of boasting”.
But in court, prosecutors argued differently, outlining the case against Davis and three other British men arrested at the same Istanbul apartment.
A series of phone calls are said to link the group.
The papers also give full details of the other British suspects held as part of the investigation.
They include Deniz Solak, 32, from east London who has dual UK and Turkish citizenship, and told police he made annual trips to Turkey for some time "to see the motherland".
Solak also claims to have been in Syria carrying out charity work, and denies the allegations against him.
He said he had recently settled in Turkey because of the influence of a third suspect, Jermaine Burke, a friend from London’s boxing rings.
Burke told Turkish police that he travelled to the region in 2014 to help deliver 111 lorry-loads of aid sent from Britain.
He said he worked in Turkey as an English teacher, and had never crossed the border into Syria.
A fourth British suspect, 39-year old Muhammed Karwani, told Turkish counter terrorism officers that his only crime was to love Turkey.
He said he had been staying in the country since 2013, most recently in the southern city of Konya, but travelled to Istanbul for a job interview three days before his arrest.
Two other men - from Jordan and Saudi Arabia - are charged alongside them, accused of ‘membership of an armed terrorist organisation’. They all deny the charges.
British authorities today told ITV News they were unable to confirm whether they would seek to extradite Davis or the other British suspects following their prosecution in Turkey.
But Turkish courts do not routinely share information about UK suspects, so information about their case has been difficult to obtain by British diplomatic authorities.