The teenager who murdered teacher Ann Maguire has been named as 16-year-old Will Cornick.
A judge at Leeds Crown Court lifted a court order previously banning the naming of the minor.
The boy was sentenced to life with a minimum of 20 years after admitting the murder of Mrs Maguire.
No one in authority could have reasonably foreseen the murder of teacher Ann Maguire, police say.
Chief Superintendent Paul Money of West Yorkshire Police said there was "absolutely no justification" for the hatred Ann's schoolboy killer felt.
Speaking outside Leeds Crown Court, where the boy was jailed for life, he added: "His motive seems inexplicable.
"I can't name the person responsible but I can say he comes from a good home, decent responsible parents, who are in their own way victims themselves of this terrible act."
The judge who presided over the Ann Maguire murder trial has slammed 'ill-informed commentators' who criticised him for naming Will Cornick.
A teenager who has admitted murdering his teacher came from a loving home and was thought of as a good student and in many ways normal.
Ann Maguire was just months away from retirement when she was stabbed to death in front of horrified pupils at a school in Leeds.