Kadiza Sultana was one of three high school young ladies who fled east London and entered Syria by means of Turkey a year ago.
The 17-year-old was living in the dread gathering's fortification city of Raqqa and is dreaded to have been slaughtered a couple of weeks back, her family's specialist has told Sky News.
Her family say they were wanting to get her over the fringe and into Turkey before she passed on, after she got to be disappointed with life in Syria.
Shamima Begum and Amira Abase were both 15 when they cleared out Bethnal Green with Kadiza in February 2015.
They had told their families they were going out for the day.
Metropolitan Police Commissioner Sir Bernard Hogan-Howe has beforehand said the young ladies would most likely not be indicted on the off chance that they came back to Britain, unless it could be demonstrated they had perpetrated violations with IS.
Government Security Minister Ben Wallace said it demonstrated the dangers some youngsters confronted from radicalisation.
He said: "These heartbreaking reports demonstrate how Daesh's harmful account can destroy families and devastatingly affect people and groups.
"We presented the Prevent obligation a year ago to make it a legitimate necessity for schools and other key establishments to have due respect to averting powerless individuals in their consideration from being drawn into terrorism. We have prepared 550,000 forefront laborers to recognize the indications of radicalisation and upheld several group drove ventures.
"Ensuring youngsters is work for every one of us. On the off chance that you are worried that you or somebody you know might be defenseless against radicalisation - converse with somebody you trust, whether that is an instructor, cop, the private NSPCC helpline or a group pioneer."
Work MP for Bethnal Green and Bow, Rushanara Ali, told Sky News: "On account of the three young ladies who went to Syria from my body electorate, there were issues about the absence of correspondence between the school, police and the families.
"What's more, that was the subject of a conciliatory sentiment by the Met.
"What we have to know going ahead is that lessons have been educated and that different families get the assistance and exhortation they require."