A woman who killed her mother murdered a stranger in the street following a series of police blunders, a watchdog said today.
Nicola Edgington, 32, made five 999 calls on the day of the attack asking to be sectioned under the Mental Health Act because she believed herself to be a danger.
But hours later she was still at large and took a knife from a butchers shop before she almost decapitated grandmother Sally Hodkin, 58, and attempted to murder Kerry Clark, 22.
The 2011 killing, in Bexleyheath, south-east London, came after Edgington - who now faces life in prison - was released back into the community in 2009.
An investigation by the Independent Police Complaints Commission (IPCC) found local police in Greenwich were not notified that she was living in the area after an order for her indefinite detention was lifted.
The watchdog also found Met staff failed to carry out a police national computer (PNC) check on Edgington when she made contact with officers on October 10 2011, shortly before the murder.
This would have alerted them to her previous conviction for the manslaughter of her mother in Sussex, the IPCC said.
Hours before she killed, Edgington sought help at a local hospital from where she called 999.
But after delays in admitting her, she walked out.
The IPCC found officers only contacted the hospital following her fourth phone call and said Edgington's second 999 call from the A&E department was downgraded because she was considered to be in a place of safety.
An officer was not dispatched at this stage despite Edgington's claim she could be very dangerous, it found.
IPCC commissioner Sarah Green said it was of "great concern" that police did not carry out a PNC check.
"This tragic case has robbed a family of a much-loved wife, mother, grandmother and friend and my thoughts again go out to Sally Hodkin's family," she said.
"Nicola Edgington had a violent history linked to her mental health problems and was evidently aware that she was a threat to others.
"On Monday 10 October 2011, she made repeated phone calls to police asking to be sectioned under the Mental Health Act and warned officers in person of the risk she posed to those around her.
"While our investigation found that no police officers or staff breached the code of conduct, it is of great concern that no PNC check was carried out which would have immediately alerted them to Edgington's violent history.
"Without this PNC check, both the police and staff at Queen Elizabeth Hospital, Woolwich were without crucial information which may have influenced their future decisions, increased the urgency of the situation and could have escalated the medical attention she was given."