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The masked Islamic State militant known to us all as “Jihadi John”, the man shown in the videos of the beheadings of Western hostages; has been, for the first time, named.

He is Mohammed Emwazi, a Kuwaiti-born British man in his mid-20s from west London. He had according to the most recent reporting been “known to British security services.”

British police declined to comment on this most recent development, citing that this is currently an ongoing investigation. Emwazi appeared first in a ISIS video last August, when he killed the US journalist James Foley. He is also thought to have been the man pictured in the videos of the beheadings of US journalist Steven Sotloff, British aid worker David Haines, British taxi driver Alan Henning, and American aid worker Abdul-Rahman Kassig.

In each of these horrific videos, the militant appeared dressed in a black robe with a black balaclava covering all but his eyes and top of his nose. Speaking with a British accent, he would go on to speak hatefully towards Western powers before holding his knife to the hostages’ necks, appearing to start cutting at his victim before the film would abruptly stop. The victims’ decapitated bodies were shown when the video reconnects.

Earlier this month, the militant featured in a video in which the Japanese journalist Kenji Goto appeared to have been beheaded as the other hostages. Hostages released by Islamic State have said he was one of three British jihadists guarding Westerners abducted by the group in Syria. They were known collectively as “the Beatles”.

In a news conference, Asim Qureshi, the research director of the London-based human rights group Cage, which had been in contact with Emwazi for a number of years, detailed the difficulties Emwazi had with security services in the UK and overseas. Mr Qureshi said Emwazi, who is believed to be in his mid to late 20s, had been “extremely kind, gentle and soft-spoken, the most humble young person I knew”. Qureshi said he could “not be 100% certain” Jihadi John was Emwazi although there were “striking similarities”.

Emwazi’s difficulties, according to Mr Qureshi, began when he travelled to Tanzania in May 2009 following his graduation in computer programming at the University of Westminster. He and two friends had planned to go on a safari as a gift to themselves for graduating but once they landed they were detained by police and held overnight.

Emwazi aborted that particular venture and ended up flying to Amsterdam, where he claimed he was met by British intelligence agents from MI5 who accused him of trying to travel to Somalia, where the jihadist group al-Shabab operates. He denied the accusation and said the agents had tried to recruit him before allowing him to return to the UK.

To put things simply this man was a “person of interest” to British intelligence going back as far as 2009 or 2010; we know this because he features in court case relating to extremism overseas and back in the UK.

Yet Emwazi was able to travel abroad and join up with this massively extremist organisation. Knowing who this man was does not bring us closer to stopping what ISIS is doing; nor will have a name attached to their murders help the families of those ISIS have killed. It does mean we know who is responsible. We know who can be blamed for depriving families of men who they loved. We certainly know Emwazi will not be able to return to England ever again unless he is chains. Hopefully there is some comfort for the families in knowing that the man who killed their loved ones will face justice someday soon.