A UK teen girl who joined the Islamic State is believed dead

A teen girl who left her home in east London last year to join Islamic State militants in Syria is believed to have been killed by a Russian airstrike.

Kadiza Sultana was 16 years old when she and two friends from school, Shamima Begum and Amira Abase, secretly flew from Gatwick airport to Istanbul in February 2015 and crossed into Syria. It's believed they were living in Raqqa, an Islamic State stronghold.

Their cases shone a spotlight on IS's aggressive efforts to groom young Westerners, particularly young girls, to join their cause.

The Sultana family's attorney Tasnime Akunjee told BBC Newsnight on Friday that they heard reports she may have died several weeks ago, but have yet to verify the information.

"By all accounts, she was a young girl with a very promising future and it's a great loss to us all really," Akunjee said. "Every effort was made from the beginning to avoid this fateful news."

According to ITV, it's believed that Sultana was killed in an airstrike in May while she was planning to flee.

Akunjee said that Sultana had become disillusioned with IS over the last year and wanted to come home. "I think she found out pretty quickly that the propaganda doesn't match up with the reality," he said. Last July, the Telegraph reported that the the girls had been kept under close surveillance in a compound by IS jihadis. They were reportedly married off to fighters shortly after they arrived, although two became widows.

However, Akunjee said Sultana stayed over fears she would be punished by UK law enforcement upon her return.

Watch the VICE News documentary, The Girls Who Fled To Syria: Groomed By The Islamic State here:

The girls and their families had been embroiled in an ongoing counterterrorism investigation in the UK, until the head of the London Metropolitan police's counter terrorism branch announced the force had no evidence with which to charge them with terror-related crimes.

VICE News spoke to Amira Abase's father after that announcement last March for a documentary. "When I think back over my life's history, generally, living here in England, I would have never dreamed … [my] daughter missing. One day, maybe, I'll see her and talk. Even forget this day, and as if nothing happened, we can go forward."

Last year, it was reported that a fourth student from the girls' school, Sharmeena Begum, went missing in 2014 to join ISIS in Syria. Multiple sources working on their cases told VICE News in 2015 that Sharmeena had attempted to radicalize the three other girls before they left.

Other experts who work on deradicalization in the UK have previously told VICE News that it's common for radicalized young women to bring other young women into the fold.

In June, a study in the journal Science Advances found that women who support the Islamic State serve as more than just "jihadi brides" and that their support online through social media can be subtle but very powerful in terms of bringing in new recruits.

Follow Rachel Browne on Twitter: @rp_browne