MATTHEW Daley was a quiet and respectful child who never barged in front of the other people in the queue at school.

Growing up with a brother and sister in Worthing, he got good exam results before going to Chichester College to do a building studies course where he finished top of his class.

From there he went to Portsmouth University to study architecture, and once made his parents “beside themselves” with worry by suddenly jetting off to Argentina.

“He had got his cheque for his grant and one afternoon he was looking at a book and was interested in this building in Argentina,” his father John Daley recalled.

“He decided he would like to go and see it so that day he just picked up his passport and flew out to Argentina.”

In 2005, Daley went to live in a bedsit in Worthing; his parents were pleased he was becoming more independent, but warning signs of serious illness appeared.

When Daley complained about noisy neighbours, his parents thought at first he was just making a fuss, but later came to realise these were the auditory hallucinations plaguing their son.

At times the voices got so bad he shaved his head to try to get rid of them and he turned the fridge in his flat to face the wall because he believed it was causing him problems in the head.

In July 2008, Daley was diagnosed with Asperger’s and psychosis and prescribed low doses of olanzapine, an anti-psychotic.

But he stopped taking the drug, his family said, partly because he did not always believe he was ill and did not like being labelled with a mental health problem.

Paul Farmer, chief executive of mental health charity Mind, said “stigma and misunderstanding” around mental health problems did stop people speaking out and getting treatment.

He added: “What’s important is that people are treated as whole people, not just a diagnosis, and that they get the right care and support.”

Experts have also come to believe that the early diagnosis of Asperger’s for Daley came to cloud subsequent treatment.

He came under the care of the Sussex Partnership NHS Foundation Trust in 2008, and its chief executive Colm Donaghy says the team’s subsequent close relationship with him may have got in the way of their looking more closely at his psychosis.

He was diagnosed with paranoid schizophrenia after his arrest for killing Don Lock on July 16 last year. Doctors believe he may have had the condition since 2008.

In June 2012, his father wrote to doctors asking for his son to be sectioned after he smashed a friend’s car with a hammer.

Again in December 2012, his father asked for his son to be sectioned and also wrote to doctors in September 2013 and March 2014.

In that month, Daley made several 999 calls to Sussex Police about the voices, which he believed were men saying nasty things about him outside his flat.

A police community support officer met him and told him to stop calling the police, a spokesman for the force said.

Asked whether the force had told his mental health team about the calls, the spokesman did not give a clear answer.

He said they were “satisfied” that “all information sharing protocols were followed”.

In July 2014, Daley’s father took him to hospital and asked for him to be sectioned, but his son was given more drugs.

Marjorie Wallace, chief executive of the mental health charity SANE, said families not being listened to enough was a problem in 55 per cent of 100 homicides her charity had looked into.

She said: “In many cases, the tragedy would have been preventable and I believe that in this case it would have been completely preventable.”

In court, Daley’s mother, Lynda, spoke of the efforts she had made to try to convince others that her son was as mentally unwell as she knew him to be.

Her son’s defence barrister, David Howker QC, said it was fair to describe her as an “expert on your son”.

Mrs Daley told jurors: “If you asked him about something, he would put the barriers up and would not want to discuss it.

“You cannot understand Matthew in a short meeting of one or two hours, you need to be with him a long time to understand the way he processes things and deals with things. As a family, we could all recognise the signs.”