By Milena Veselinovic CNN

LONDON (CNN) -- Relatives of one of three British schoolgirls who left the country last year, apparently to join ISIS in Syria, fear she is dead, a family attorney said Thursday.

Kadiza Sultana, then 16, and two other teens boarded a Turkish Airlines flight from London's Gatwick Airport to Istanbul on February 17, 2015. They were thought to have crossed the border into Syria within days.

Tasnime Akunjee, who represents Sultana's family, said the family received news of her death in Raqqa "some weeks ago," at the same time communication from her stopped. Akunjee said he had been working with the family to try to bring Sultana back to London.

Reports of Sultana's death have not been independently confirmed.

The UK Foreign Office said, "It is extremely difficult to confirm the status and whereabouts of British nationals in Syria as all UK consular services there are suspended."

The Guardian newspaper, citing family members, reported last year that two of the teens married men approved for them by ISIS.

The three girls caused consternation when they left the United Kingdom, apparently without warning, and went to Syria. A packing list they left behind looked like one any teenage girl might make before leaving on vacation: makeup, bras, underwear, boots, an epilator, according to the Guardian, which saw the list.

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