A grandmother was killed by her "devil-obsessed" grandson who had undiagnosed and untreated schizophrenia.
Conor Clarkson, 30, claimed he was Lucifer and beat Marlene McCabe, 71, with a doorstop at their home.
An inquest heard Ms McCabe and her daughter Sharon Clarkson had pleaded with medics for help for Mr Clarkson, who had been displaying "bizarre and worrying behaviour" in the weeks before the tragedy.
Mrs McCabe had started barricading herself into her bedroom at night in early 2019 after Mr Clarkson began making frightening comments about death, murder and evil.
A coroner ruled last month the pensioner died as a result of an unlawful killing, Lancs Live reports.
But the inquest at Blackpool Town Hall heard how a string of medical professionals failed to recognise the man was suffering from a severe form of paranoid schizophrenia, and a prevention of future deaths report issued this week highlights steps to prevent similar tragedies.
Family members described how Mr Clarkson, who had been placed in the care of his grandmother as a young child, had become increasingly paranoid.
"He was convinced something was going to get him," Andrew Scott, the partner of Mrs McCabe's daughter Sharon, said.
In May 2019, Ms McCabe handed in a 10-page letter to Bloomfield Medical Centre in Blackpool, voicing her concerns about her grandson. Dr Paul Collins referred Mr Clarkson for a mental health assessment but failed to specify the referral was urgent. He admitted during the inquest that this "was a mistake on my part".
Just weeks before Mr Clarkson killed Ms McCabe at their home in Blackpool, his family had called 999 after he began acting aggressively and declaring that he was 'Lucifer'. Mr Clarkson was taken to Blackpool Victoria Hospital by paramedics, with a police officer accompanying him into A&E.
An A&E nurse who triaged Mr Clarkson was alarmed to see him crouching on a chair and hissing at people and he was assessed by mental health team leader Carole Middlebrook. Extracts of medical records suggested that Ms Middlebrook's assessment of the man lasted less than nine minutes and she decided he was a "nice young man" with "no underlying psychosis".
Dr Richard Morgan, who was the acting medical director of Lancashire and South Cumbria NHS Foundation Trust at the time of Marlene's death, later held a meeting with those involved in Mr Clarkson's care. Medics claimed Dr Morgan had told them her death "could have been avoided".
Just days after Mr Clarkson's visit to A&E his aunt Sharon went to the hospital in person with a 10-page letter and warned she was terrified something was going to happen. The most senior clinician present at the time, Michelle Fury, refused to speak to Mrs Whitlow and instructed reception staff to inform Mrs Whitlow that "we're not an emergency service and to ring police if they're frightened."
A Home Office Domestic Homicide Review carried out following Ms McCabe's death found that two incidents in December 2017 and a further incident in 2019 were not recognised as domestic abuse and therefore policies and procedures were not followed.
In a report to prevent future deaths, the coroner Tim Holloway wrote to Bloomfield Medical Centre, Blackpool Teaching Hospitals NHS Foundation Trust, Lancashire and South Cumbria NHS Foundation Trust and North West Ambulance Service, stating: "On 4th September 2019, between around 5.10pm and 5.50pm, Marlene McCabe was killed unlawfully in her own home.
"She died as a consequence of being struck a multiplicity of times to the head and face with a blunt object, namely a doorstop, which occasioned catastrophic head and facial injuries. The actions of her assailant were more than minimally contributed to by the assailant's undiagnosed and untreated schizophrenia coupled with alcohol intoxication.
"There were accepted prior failures in the collation and consideration of information, including from the available records and family, and in the mental health assessment of and progression of treatment for the assailant, in particular from early July 2019, which did not more than minimally contribute to Marlene McCabe's death."
The coroner raised concerns about the potential for a lack of understanding amongst clinicians as to how urgent referrals into the PIMHT should be made. He also highlighted inconsistent availability of access to mental health records across the service providers and said information sharing between service providers using different data bases is difficult.
He said there was a risk relevant material about a patient's mental health was not communicated between healthcare providers.
Additionally, Mr Holloway raised concerns about substance misuse, saying: "There is a residual risk that reference to drug and/or alcohol misuse in mental health referrals and/or assessments may lead to the missing of a mental health diagnosis and that circumstances may arise in which assumptions are made concerning substance misuse.
He added: "There is a risk that delayed assessment of patients who may appear to be or are reported to be intoxicated will give rise to a loss of opportunity to identify signs of psychosis."
The coroner asked for the healthcare providers to provide a response to the concerns raised within 56 days, by August 7 2023. He said he believes the organisations have the power to take action to prevent further deaths.
