Jihadi bride Shamima Begum could be arrested if she arrives at the UK border, the head of the Met Police has said.
Metropolitan Police Commissioner Cressida Dick said the 19-year-old could expect to be "spoken to" if she comes back to Britain.
On Tuesday, Ms Dick said: "If she does, under whatever circumstances, arrive at our borders, somebody in her type of circumstances could expect, of course, to be spoken to and, if there is the appropriate necessity, to be potentially arrested and certainly investigated.
"If that results in sufficient evidence for a prosecution then it will result in sufficient evidence for a prosecution.
"The officers will deal with whatever they are confronted with."
The initial police stance when Ms Begum left the UK in 2015 was that she may be treated as a victim of grooming, but the Scotland Yard chief said on Tuesday: "We're a long way down the road since then."
Her comments come as Home secretary Sajid Javid said a rewrite of Britain's 650-year-old treason law could be implemented to prosecute returning jihadis.
Mr Javid told the House of Commons on Monday that a change to the 1351 Treason Act was "worth considering carefully".
He said: "This is a complex situation and we should always be looking to see what tools we have at our disposal to ensure that those who are guilty of terrorism, or of supporting terrorist groups, are brought to justice.
"That means ensuring that we have the right laws in place. There are already powers in existence, including those covering extra-territorial jurisdictions."
Mr Javid has said that no British troops will be used to rescue any Britons who travelled to Syria to support terrorism, and vowed to block Ms Begum's return.
IS supporter Shamima Begum admits to @BBCNews she was a poster girl for IS recruitment, apologises to Britain for joining IS and says she is ready to face prison if she's allowed to return. pic.twitter.com/KkYAWd4pnN- Quentin Sommerville (@sommervilletv) February 18, 2019
In an interview with the BBC's Middle East correspondent, Quentin Sommerville, Ms Begum said she is ready to face prison if it means returning from a Syrian refugee camp to the UK with her baby boy, who was born on Saturday.
The 19-year-old said: "I actually do support some British values and I am willing to go back to the UK and settle back again and rehabilitate and that stuff."
She left east London along with two other teenage girls in 2015 to join Islamic State in Syria, but now wants to return home.
She later told ITV News she did not see why Home Secretary Sajid Javid would see her as a threat.
"I'm a 19-year-old girl with a new born baby. I don't have any weapons; I don't want to hurt anyone even if I did have weapons or anything," she said.
"He has no proof that I was a threat other than that I was in Isis, that's it. I don't know how I would be seen as a danger.
"I'm not going to go back and promote people to go to Isis or anything, if anything I'm going to encourage them not to go because it's not all it seems in their videos.
"I do regret it because when I went I thought I was going to make a family and I didn't realise what the things they were doing that they weren't showing in their propaganda videos, and I actually do regret it, I do feel bad for anyone who was affected by the actions of Isis."
But Ms Begum had earlier caused controversy by comparing the Manchester Arena bombing to military assaults on Syria.
In her interview with the BBC, she said the deaths of 22 innocent people in the terrorist attack on an Ariana Grande concert in 2017 were akin to the "women and children" being bombed in IS territory in Baghuz.
She said: "I do feel that it's wrong that innocent people did get killed. It's one thing to kill a soldier that is fighting you, it's self-defence, but to kill the people like women and children.
"Just people like the women and children in Baghuz that are being killed right now unjustly, the bombings. It's a two-way thing really.
"Because women and children are being killed back in the Islamic State right now and it's kind of retaliation. Like, their justification was that it was retaliation so I thought 'OK, that is a fair justification'."
The mother-of-three, who gave birth to her third child at the weekend, left east London with two friends in 2015 to join the terrorist group.
She was partly inspired by videos of fighters beheading hostages and partly by other propaganda films showing the "good life" IS could offer. Since she has been there, her two older children have died.
UK authorities now face the difficult question of what to do if Ms Begum manages to return to Britain.
Her family's lawyer, Tasnime Akunjee, said he anticipated she would face criminal proceedings upon any return to the UK, but that it was the family's hope she would be given professional help following her experience in Syria.
- This article originally appeared on Yahoo UK