In the early hours of October 10, 2011, the day of the killing, police were called when she told cab office employees that she needed to be sectioned.She was taken to the Queen Elizabeth Hospital where officers helped her book in at reception at around 4.30am.
But as they left, Edgington told them she did not feel safe there. She made a series of phone calls and later 999 calls.
In one call, she said: "I'm a very dangerous schizophrenic. If you don't come and help me I'm going end up hurting someone."
Edgington was accepted to the hospital's onsite psychiatric unit Oxleas House, but was not taken there until 6.30am.
But just after 7am, Edgington said she was going to call her care co-ordinator and left. Staff called police.
Edgington calmly took two buses to Bexleyheath, south east London, and bought a large knife from an Asda supermarket, before she attacked her two victims.
Nicola Edgington has been found guilty of the murder of grandmother Sally Hodkin and the attempted murder of another woman, Kerry Clark in a knife attacks in Bexleyheath in 2011.
The Old Bailey has been told that a woman who attacked two strangers with a knife, had killed her mother six years before.
Nicola Edgington is now on trial accused of murdering one woman, and attempting to murder another in Bexleyheath on 20-11.
Paul Brand reports.
Paul Brand has the latest from the trial of Nicola Edgington, who is accused of murder and attempted murder.
The Old Bailey heard today how Two women going to work were attacked by a knife-wielding woman in Bexleyheath, East London.
Kerry Clark, 22, managed to fight Nicola Edgington off but Sally Hodkin, 58, died when her neck was cut with a large butcher's knife.
Edgington was being cared for in the community and was being monitored by a psychiatrist, nurse and social worker at the time.
Her condition had deteriorated after she stopped taking her medication, the court heard.
They were then told how hours earlier, she had gone to a hospital - but walked out before she could be admitted as a voluntary inpatient.
Edgington, 32, of Greenwich, south east London, denies murdering law firm accounts manager Mrs Hodkin in Bexleyheath, south east London, in October 2011.
She also denies the attempted murder of Miss Clark, who is now 24.
Mark Heywood QC, prosecuting, said: "She approached and deliberately and viciously attacked each of them without warning, without any provocation.
"She used the weapon forcefully and purposefully in each attack. She was controlled and she was rational."
A man and a woman have been charged with the murder of Prabjot Singh Rayat.
The 54-year-old was killed on 8th June near to the car repair shop he owned in Thamesmead.
A post-mortem found he died from a stab wound. Mr Rayat from Bexleyheath had a wife and three children.
The pair accused of his murder will appear at Bromley Magistrates' Court on Friday 15th June.
Two teenagers, who stabbed a student to death, during a row between rival schools in south-east London, are facing years behind bars.
16 year old Yemurai Kanyangarara was ambushed as he stepped off a bus in Bexleyheath last July.
16 year-old Osman Bangura was today found guilty of murder and 15 year-old Isaac Walters, was convicted of manslaughter.
A third boy was acquitted of murder.