An "exceptionally dangerous" woman who attacked two strangers with a knife has been jailed for at least 37 years.
Nicola Edgington, 32, killed grandmother Sally Hodkin, 58, and tried to kill artist Kerry Clark, 22.
She had also stabbed her mother to death six years earlier, but was released to live in the community.
Edgington suffered a sudden relapse in her mental health, two years after being released from a mental unit, in October 2011.
She was taken to a local A&E department in south-east London but walked out after becoming annoyed at being kept waiting.
Mrs Hodkin's widower, Paul, told the court that 40 years of marriage were 'wiped out in seconds'
She took a bus to Bexleyheath and attacked the two strangers who were going to work.
When Miss Clark grabbed the blade and kicked her away, Edgington ran to a butcher's shop and grabbed a larger knife.
She attacked Mrs Hodkin, a law firm accounts clerk, with such force that she almost decapitated her.
John Cooper, QC, mitigating, said she was a woman in crisis and had not been given the help she asked for.
But the Recorder of London, Judge Brian Barker, said Edgington should take responsibility and stop blaming others.
He jailed her for life with a minimum term of 37 years for murder and gave her a concurrent sentence of life with a minimum term of 20 years for attempted murder.
Judge Barker told Edgington her behaviour had been "consistent and calculated".
He said: "You are manipulative and exceptionally dangerous. What you did could not have been more selfish.
"I disagree that the responsibility for these acts can be laid on others. You made your choice and these were terrible acts for which you must take responsibility.
"You have come as near as can be to having three deaths on your hands."
Miss Clark had escaped with only cuts to her hands because of her bravery and quick action, he said.
Edgington was diagnosed with paranoid schizophrenia after stabbing her mother nine times at the family home in Sussex in 2005.
A year later, she pleaded guilty to manslaughter on the grounds of diminished responsibility and was sent to a secure mental hospital.
Doctors at the Bracton Centre said she was well enough to be treated in the community after three years.
But after two years of being monitored by a psychiatrist, nurse and social worker, her life began to unravel and her mental state deteriorated.
She was taken to the Queen Elizabeth Hospital in Woolwich by police after staff at a cab firm became alarmed at her behaviour in the middle of the night.
While waiting to be admitted, she rang 999 five times and warned that she was dangerous and would harm somebody if she was not sectioned.
After a delay, she was taken to the mental health unit, Oxleas House, but walked out soon afterwards and later complained that staff kept tapping on a computer.
The judge said: "It is unfortunate that the shift was changing and one of the doors was faulty."
The court was told Edgington had a borderline personality disorder and had been wrongly diagnosed with a mental illness.
Mrs Hodkin's widower, Paul, told the court in a statement: "Forty years of marriage gone, wiped out in seconds by someone that should not have been on the streets."
His solicitor, Daniel Rubinstein, said outside court: "While the family are relieved that a very dangerous woman has been taken off the streets, they remain concerned at the very many questions that remain over the actions of authorities and the alleged failure to treat clearly dangerous people in a secure environment.
"They will be considering further action to get answers, in the hope that other families won't have to go through the same appalling experience that they have."
The sentencing came on the day that the Independent Police Complaints Commission found failings in the case.
It found that local police in Greenwich were not notified that Edgington was living in the area.
Police and police staff did not carry out a police national computer check which would have alerted them to Edgington's previous conviction for manslaughter.
And after she left, the call from the doctor was not marked up for immediate attention.
Scotland Yard said later in a statement: "The IPCC have not made any recommendations but we recognise the need to continuously review our policies and procedures to ensure that officers and staff receive the most suitable and up to date training and that they act with total professionalism and integrity at all times."Suggest a correction