His mother says he was groomed by drug gangsters despite her attempts to get help. Let his death spark fresh debate about how we care for vulnerable people

The last time Mary Bokassa saw her 14-year-old son alive was around lunchtime, on his first day back to school after Christmas. She had no way of knowing that within an hour and a half, her child would be dead, stabbed 12 times on a bus in broad daylight in Woolwich, south London.

And yet, as his mother explained in a bleak and haunting interview, his death was a shock but not a surprise. Her son Kelyan had been targeted by gang members trying to recruit him since he was six, she told the BBC: “I tried to prevent it. I’ve tried so many, so many times. I screamed it, I said, ‘My son is going to be killed.’” But the family hadn’t, she said, got the help they needed. She had fought for her little boy and she had lost, and there is something about the starkness with which she said it that will have stopped parents across the country in their tracks.

Gaby Hinsliff is a Guardian columnist