Inevitably, the debate following the stabbing to death of Sebastian Creane by Shane Clancy has concentrated on knife crime.

But would it not be more constructive if we focused attention on the less headline-friendly but more pertinent issue of mental health services – or lack of them – for young people diagnosed with serious mental illnesses that often require the prescription of mind-altering medication?

As the gardaí and media try to piece together a narrative of the events of last weekend in Bray, Co Wicklow that left Sebastian Creane murdered, his killer Shane Clancy dead through suicide, and two other young people seriously injured, questions have inevitably been asked about what sort of society we are becoming and whether violence is endemic.

Why would a 22-year-old university student even think of going out of his way to buy a knife to inflict harm on the man now going out with his ex girlfriend, even taking into account the fact that his mind was clearly unbalanced? Why not use his fists in this moment of derangement, an action bad enough of course, but one less likely to end in death and terrible injury?

Is it because knives are such a part of the psyche of our younger generation now that, even in this middle-class environment where the samurai swords and flick knives of gang culture are alien, and most certainly so to a third-level student of the bible, with a job to subsidise his studies and a genuine interest in charitable work, that when passion took over from sense they were immediately turned to?

Even to those who see fearful influences in every corner of society, this explanation must seem far-fetched – all the more so as information about the sort of person Shane Clancy was begins to emerge.

The priest at his funeral tried to express the feelings of incomprehension – and yes, revulsion – that everyone feels about the violence of last Sunday. "We are greatly shocked by the psychotic state and destructive frenzy in which his mind suddenly entered, so uncharacteristically," Fr John McDonagh told mourners. "Only a few gifted people whose job it was to make sense of such behaviour would understand what has mystified everyone else."

So much of what has been written about what happened has been untrue or only half true that the real facts may never emerge.

But while the physical post-mortems have been completed, if ever there was a need for a psychological post-mortem to take place, this is one. And if it is to mean anything, that investigation should extend to how well Shane Clancy was served by our mental health services.

From what we know now, it seems Clancy – a teetotaller in a world where binge drinking is common – had recently been diagnosed with depression and was on medication for it.

Maybe he failed to take his medication, or took too much of it, or reacted badly. Whatever happened, the final year Trinity College student who lived in a small flat on his own experienced a psychotic episode.

This does not make him evil, as some have tried to portray him. It makes him a young man among many young men in this country suffering difficult-to-manage chronic mental illnesses within a society that still regards psychiatric conditions as a stigma, who are served by a mental health system that is itself chaotic, underfinanced, fractured and dysfunctional.

Not all young people with psychiatric problems ever have a psychotic episode, or are even remotely violent. But far too many – often young men – end up in a revolving-door lifestyle circling from mental hospital to bedsit or bedroom of the family home, minds confused by the powerful drugs used to control their illness, utterly despairing of any way out. Many are literally abandoned after diagnosis to pills and isolation. There is an entirely inadequate support system to help them and their families gain insight into managing their illness. The sort of long-term counselling, group therapy and support groups which help those with mental illness see a future, and which act as a bulwark in times of stress – such as the break-up of a relationship – are pitifully under-resourced.

The Vision for Change policy, adopted three and a half years ago at government level, was supposed to change all that. But today, this fundamental reform of our mental health services which envisaged a community-based, people-centred system and gave those with difficult psychiatric illnesses hope and support, has been parked. Mental health services in these times, to our shame, rank among the lowest of priorities.

Two young people are dead. Two others have been very badly injured. Last week's events have left two families changed forever, friends grieving and the local communities in a state of shock.

It is a tragedy of terrible proportions. But it is made all the worse by the certainty that our mental health system will not improve one bit because of it and that, sad as we are as a society about what happened, we are not angry enough to insist on change.