William Cornick's murder of Ann Maguire is probably one of the most shocking events I can recall reading about.
He has been sentenced to a minimum of 20 years in prison. He has not apparently been diagnosed as being mentally unstable.
And yet how can anyone say that he isn't suffering from some sort of mental illness?
Apparently he had made threats to kill Mrs Maguire many times, including on Facebook.
But at the trial the judge seemed to accept that there was no prior indication that this terrible crime was likely to occur, citing his middle-class upbringing and his apparently bright demeanour at school.
What should we do about young men like him, and how can we ensure that something like this doesn't happen again?