It has been reported that the man seen shooting a prisoner in the head in Daesh's latest propaganda video is 32-year-old former bouncy castle salesman Siddhartha Dhar from East London.
British media have reportedly spoken to family and former neighbors of Dhar, who believe that he is the Daesh spokesperson in question.
The suspect's sister Konika Dhar said that while the man in Daesh's video did sound like her brother, she wasn't entirely convinced that he was the man in question, who has been dubbed the new 'Jihadi John'.
"If it is him, bloody hell am I shocked? I am going to kill him myself. He is going to come back and I am going to kill him if he has done this," she said from her home in London.
"I can't believe it. This is just so shocking for me. I don't know what the authorities are doing to confirm the identity, but I need to know if it is."
Siddhartha Dhar, aka Abu Rumaysah, widely believed to be masked man in IS video, told me in 2014 — 'we are in the middle of a global war'— Sian Williams (@sianwilliams100) January 5, 2016
Suspect Fled UK on Bus
Dhar, a British-Indian Muslim convert who also goes by the name of Abu Rumasayah, has long been known to UK intelligence and was arrested in September 2014 alongside controversial preacher Anjem Choudary for allegedly being part of the banned group Al-Muhajiroun.
However, just hours after being granted bail, Dhar caught a bus with his family to Paris, where he then traveled onwards to Syria to join Daesh.
@SkyNews now saying the the new suspected "Jihadi John" didnt hand in his passport,just went home on bail packed his things & left!! Farce— Grumpy Old Lady (@annispice) January 5, 2016
Once he arrived in Syria, Dhar took to social media to taunt British intelligence, tweeting: "What a shoddy security system Britain must have to allow me to breeze through Europe to the Islamic State."
"When we descend on the streets of London, Paris and Washington the taste will be far bitterer, because not only will we spill your blood, but we will also demolish your statues, erase your history and, most painfully, convert your children who will then go on to champion our name and curse their forefathers," he wrote.
British Intel Red-Faced
His escape has led to heavy criticism of British intelligence and security agencies for allowing him to slip through the cracks and leave the country despite being on bail over terrorism offences.
Dhar was alleged to have been a key member of al-Muhajiroun, who often traveled around London trying to recruit troubled youths to Islam.
British intelligence believe they know who the new Jihadi John is- PM's spokesman says an "initial assessment" has been made. No names.— Craig Woodhouse (@craigawoodhouse) January 5, 2016
He had spoken to a range of media outlets such as the BBC, and in an interview with VICE News in 2013 he professed his support to a Syria-based Islamic state.
"We believe that whenever the Sharia is established, the pure Islamic state maybe in Iraq or Syria, one day the leader will wage jihad and annex Britain into the Islamic state.
"We are not going to forget Europe, we are not going to forget Britain, the armies will be sent here to conquer these lands," he said.
While intelligence services aim to determine the identity of the man in the Daesh propaganda video, Raffaello Pantucci, director of international security studies at Royal United Services said the man's accent suggests it could be Dhar, or someone else who from London.
"He sounds a bit like Abu Rumaysah [Dhar] from Al-Muhajiroun videos. From watching him in Al-Muhajiroun videos and this new video he sounds very similar," Pantucci said.