Why do we ignore the mental health aspects of crime?
When 16-year-old Will Cornick admitted murdering the schoolteacher Ann Maguire, the reaction was one of shock and bewilderment.
How could a schoolboy have carried out such an appalling crime?
Cornick stabbed the Spanish teacher seven times in her back and neck in a classroom at Corpus Christi Catholic College in Leeds. At the time of the murder, in April, he was 15 years old.
What made the brutal killing so apparently inexplicable to people was the boy's background.
The court was told his family life was marked by "love and support", his parents were "decent and responsible" and he had received "generally positive" academic reports.
A former student said Cornick was "probably the most intelligent person" he knew.
In fact, pupils had noticed disturbing aspects to the teenager's personality - and after murdering Mrs Maguire, he was assessed by a psychiatrist as having a disorder with "psychopathic tendencies".
Following the case, however, there was remarkably little comment about what a personality disorder actually is, how it comes about, whether it is treatable and the circumstances in which it can arise in someone from an apparently "normal" family.
David Wilson, professor of criminology at Birmingham City University, says murder cases usually become a "whodunnit" or "whydunnit", and in the Cornick case the "whodunnit" issue had been solved while the "whydunnit" question was "too difficult" to contemplate.
"The 'whydunnit' element couldn't be easily explained, therefore the whydunnit element didn't dominate," says Prof Wilson.
Instead, coverage was driven by the emerging details of the crime, the rights and wrongs of the judge's decision to name the schoolboy killer, and the harshness or not of his 20-year minimum jail term.
Difficult internal world
Paula Conway, a consultant clinical psychologist who specialises in child, adolescent and family work, says it illustrates a wider problem - our difficulty in understanding issues relating to mental health.
"People don't have an easy language to answer those questions - and they don't have a language to talk about the mind and the internal world," she says.
Ms Conway says the failings of institutions and systems are magnified - whereas family issues that don't lend themselves to a superficial analysis are brushed under the carpet.
"People are very reluctant to think about the possible impact of family relationships and lives on a young person's development and that those cases could have anything to do with an upbringing," she says.
The pattern in murder cases, in which those involved have had contact with state agencies, is for there to be an inquiry, review or investigation into the role of social workers, police officers, probation staff and others to see whether the perpetrator could have been stopped or the crime prevented.
One of the largest such reviews was the public inquiry, chaired by Mr Justice Keith, into the racially motivated murder at Feltham Young Offenders' Institution of Zahid Mubarek in March 2000.
Mubarek, 19, was beaten to death with a wooden table leg in his prison cell by a fellow inmate, Robert Stewart, known to have racist views. The public inquiry began in November 2004 and reported in June 2006.
Imtiaz Amin, Mubarek's uncle, says it was a "worthwhile" exercise and maintains there is an important place for such inquiries.
"They're definitely worth it - to raise the issue and keep people informed and educate parts of society who don't know about a particular issue."
The inquiry into Mubarek's murder found 186 failings by the Prison Service and made 88 recommendations.
But in June, eight years on, HM Inspectorate of Prisons revealed that many of the suggested reforms had not been implemented.
It said work was still "urgently required" and such a murder "could happen again".
"The failure is in the follow-up," says Mr Amin.
"Inquiries are quite good at pinpointing the issues, but they're not good at tying down the body or the government and ensuring the government will implement recommendations.
"It was left to my family to monitor the recommendations," he adds.
Prof Wilson, himself a former prison governor, questions whether jails are any safer now for inmates than they were when Mubarek was killed.
In 2013-14, amid rising levels of self-harm, suicide and serious violence, there were four homicides in prisons in England and Wales.
"I'm sick and tired of reading a statement that 'lessons will be learned', because we know they never are," Prof Wilson says.
He points to the MacPherson inquiry into the Stephen Lawrence murder as one of the few reviews that has brought about real change, particularly in terms of the public's understanding of racism and how it's policed.
The 2004 inquiry into vetting failings that allowed Ian Huntley to be employed as a school caretaker in Soham, where he murdered the schoolgirls Holly Wells and Jessica Chapman, also led to far-reaching reforms, not least because the chairman, Sir Michael Bichard, insisted on monitoring whether his proposals had been put into effect.
But there remains a sense in which inquiries simply add to the blame-game, identifying faults with systems, chastising individuals who haven't followed procedures, when the problems are deeper and more complex.
Ms Conway says the common finding she has observed from serious case reviews into killings by "disturbed" people is the failure of those charged with looking after them to communicate with each other properly.
That, she says, is because the professionals involved struggle to reconcile their differing responses to "disturbed" people.
Ms Conway says we need to develop a more mature understanding of the way in which such individuals behave and how difficult that sometimes makes it to spot and act on the warning signs.
"People who kill people are very, very disturbed," she says.
"How do very, very disturbed people communicate? In very disturbed ways."
As child protection experts review the Cornick case and whether the murder of Ann Maguire could have been prevented, that may well be a factor they take into account.