The 19-year-old, who reportedly has just given birth to a baby boy, was one of three schoolgirls, along with Kadiza Sultana and Amira Abase, from Bethnal Green Academy who left the UK to travel to Syria in February 2015.
The teenager has said she wishes to bring up her baby in the UK, and her family have begged for her to be shown mercy and to be allowed to return to east London.
The chief executive of counter-extremism organisation Quilliam, Haras Rafiq, said he “absolutely” understood that the public would be concerned about the prospect of Ms Begum’s return, but that the “intellectual and right thing to do” was for her to go before the courts.
And the parents of Aqsa Mahmood, who left Glasgow to travel to IS-held territory in 2013, said they would rather “see their daughter behind bars in Scotland than dead on a battlefield”.
Their lawyer, Aamar Anwar, told the Sunday Mirror: “If it was your daughter would you not want her back? Aqsa’s mother and father vociferously condemned their daughter.”
Mr Rafiq, formerly a member of a government taskforce looking at countering extremism after the 2005 terrorist bombings in London, told the Press Association: “Nobody can tell whether at this stage, without meeting her, spending time with her, whether she could be de-radicalised or not.
“What we can say is right now... she doesn’t show any remorse or regret and isn’t fazed by decapitated heads and bombs all around her, because she thought that was a normal life. Therein lies the problem.”
He added: “Based on the interview that I heard, she, at this moment in time, is not somebody who thinks she needs to be de-radicalised therefore it’s going to be a challenge for whoever does it.”
Ms Begum, who said she did not regret travelling to IS-controlled Syria, said she understood she could face a police investigation if she returns
Mr Rafiq said she would not be obliged to participate in the voluntary deradicalisation programmes when released from jail and reunited with her child if she were to be imprisoned for terror offences.
The teenager fears her unborn baby will be taken away from her if she returns and her family, who believe she was groomed, pleaded for the teenager to be allowed back to the UK “as a matter of urgency”.
Questions have been raised over whether Britain would be able to prevent Ms Begum’s eventual return to the UK.
Home Secretary Sajid Javid has warned that he “will not hesitate” to prevent the return of Britons who travelled to join Islamic State, but Justice Secretary David Gauke said “We can’t make people stateless.”
Mr Javid wrote in the Sunday Times that many supporters of IS have returned to their home countries.