The first white British male to join Isis has been identified as Jack Letts, 20.
Letts, now known as Ibrahim or Abu Muhammed, reportedly travelled to Syria when he was 18, after converting to Islam.
He admitted to his parents he was with Isis in September 2014 and is understood to have married a woman from Fallujah, Iraq, shortly after arriving in Syria, The Times reports.
Letts reportedly comes from a secular, non-Islamic background. He studied at Cherwell school, Oxford. He is reported to have drank alcohol and occasionally smoked cannabis with his friends before converting to Islam.
His father is an organic farmer and archaeobotanist and his mother a books editor. Both are said to be extremely worried for his safety after he told them he was moving to Kuwait to study Arabic, when in fact he was travelling to Syria.
One former school friend told the paper: "At school he was very much the classroom clown and was liked by a lot of students.
"That's why this whole thing of him going to live in Syria and join Isis doesn't make any sense."
Some former school friends from Oxford reportedly named him "Jihadi Jack".
Now a frontline fighter for the militant group, he lives with his wife and son Muhammed in the Iraqi city of Fallujah, having earlier lived in Raqqa, Syria, MailOnline reports.
He is thought to have taken an interest in the Middle East during the Arab Spring of 2011. He then started learning Arabic and attended the Madina Masjid, a mosque near his home in Oxford.
There is no evidence he was radicalised at the mosque, and some of his friends believe he was radicalised in private prayer meetings.
More than 750 British men and women are thought to have joined Isis in Syria and Iraq, according to the BBC. Up to 100 of those have been killed.
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