A key witness to the alleged gas attack on Idlib, Syria, was tried in the UK for kidnapping journalists with a jihadist group.

Described in his Twitter profile as a “Medical doctor trained in the UK” and “Humanitarian aid worker”, Shajul Islam was a key eyewitness on the ground during the attack, offering himself for media video calls and uploading mobile phone footage of victims which was shared thousands of times.

OUR HOSPITAL GETTING FULL FROM THE SARIN ATTACK TODAY. ANYONE THAT WANTS EVIDENCE, I WILL VIDEO CALL YOU. — Dr Shajul Islam (@DrShajulIslam) April 4, 2017

Islam, from Stratford, East London, was interviewed by a number of mainstream broadcasters, including NBC News – but none notified viewers that he had previously been tried in the UK for terrorism offences, and struck off the medical register by the General Medical Council after a confidential tribunal.

This doctor in Syria describes the chilling reality of treating victims of chemical attacks. pic.twitter.com/IclMuvzJrM — NBC News (@NBCNews) April 6, 2017

Islam, described as a “committed jihadist” by foreign intelligence agency MI6, was tried for kidnapping John Cantlie and Jeroen Oerlemans, journalists from the UK and the Netherlands, while fighting with an Islamist group in northern Syria.

“When he told me he was an NHS doctor, I thought it was weird,” Cantlie told the Daily Mail in 2012. “This is a man who has taken an oath to save people and help them, and here he is walking around with a Kalashnikov and preaching Shariah law. There are not any doctors who I know that do that.

“He clearly believed in what he was doing but to follow something to that extreme is the disturbing thing. He was visibly upset when the execution [of two other hostages] was called off.”

Only one "Dr. Shajul Islam" has been registered in the UK. He was suspended in 2012 until he got erased last year. https://t.co/JVhGZm5G01 pic.twitter.com/tv0yXD0ZOE — Lina Arabi (@LinaArabii) April 5, 2017

The case against Islam was dropped, however, when the prosecution was unable to call Cantlie or Oerlemans to testify against him.

“The case rests wholly on their evidence [and] the prosecution is unable to call the witnesses,” said Mark Dennis QC.

He did not elaborate on why this was at the time, but it later emerged that Cantlie had been kidnapped again, this time by Islamic State, along with U.S. journalist James Foley, making it impossible for him to testify.

Fellow captive Jeroen Oerlemans refused to appear for fear this would endanger Cantlie’s life.

The Mail certainly thinks it is him, this from last year: https://t.co/FN8hZ1Myu1 — Rob Crilly (@robcrilly) April 5, 2017

Islam subsequently returned to Syria. Oerlemans was shot dead by Islamic State fighters in Libya in October 2016, and Foley was beheaded in an Islamic State propaganda video in 2014 – but Cantlie is believed to remain in captivity to this day.

He has made multiple, increasingly emaciated appearances in propaganda videos for the terror group, most recently in Mosul, Iraq, in December 2016.

Dutch photojournalist Jeroen Oerlemans killed in Libya https://t.co/6JaYEq2Frf

via @pressfreedom — ℝóí (@RoisinNiEadhra) October 11, 2016

Islam, who has always maintained his innocence, uploaded a video to his YouTube channel titled ‘British Doctor in Syria: Dr Shajul Islam’ as recently as February 2017, despite his removal from the medical register.

In November 2016 it was reported that UK Action for Refugees had raised £50,000 to fund Islam’s work in Syria, with assistance from other aid organisations.