A convicted killer who stabbed a grandmother to death in a random street attack had been freed from a secure mental health unit in Dartford just two years earlier.

Schizophrenia sufferer Nicola Edgington, 32, brutally attacked 58-year-old Sally Hodkin with a 12in butcher’s knife in Bexleyheath in October 2011.

The wound to her neck almost decapitated her.

Minutes earlier she had tried to stab another woman, Kerry Clark, as she waited to catch a bus to her work in Dartford Heath.

Edgington denied murder and attempted murder but was convicted by a jury at the Old Bailey yesterday.

The court heard she had spent three years being treated as an inpatient at the Bracton Centre, off Leyton Cross Road, after admitting the manslaughter of her mother, Marion.

She had been stabbed to death in 2005.

The unit is part of Oxleas NHS Foundation Trust, which is based in Pinewood Place, Dartford, and, according to its website, offers a range of ‘specialist forensic mental health services’ for people aged 18 to 65.

Edgington had been made subject to an indefinite hospital order under the Mental Health Act and was at the centre from 2006 to 2009.

In September that year she was released into supported accommodation in Greenwich, where she was regularly monitored by a team of medical experts.

However, the court was told she had stopped taking her medication by the time she fatally stabbed Mrs Hodkin.

Just hours earlier she had also been taken to Oxleas House in Woolwich, another psychiatric unit run by the trust, after she reportedly told a hospital nurse she might harm someone.

But she left the unit before she could be admitted and headed to Bexleyheath.

At the end of the trial Oxleas NHS Foundation Trust chief executive Stephen Firn apologised to Mrs Hodkin’s family and expressed his "sincere condolences".

But he said an investigation had concluded that the decision to release her into the community was "sound".

"The trust inquiry report concluded that the decision to recommend to the Ministry of Justice that Nicola Edgington was discharged from the Bracton Centre in 2009 was sound and the care she received in the community following her discharge was of good quality," he said.

Mr Firn added that it was a matter of "extreme regret" that Edgington, who will be sentenced at a later date, was able to leave Oxleas House before being admitted and that an independent inquiry will now be held in line with NHS requirements.

Detective Chief Inspector Graeme Gwyn of the Homicide and Serious Crime Command said: "On the morning of October 10 2011 Nicola Edgington identified her innocent victims from amongst the many members of the public, most of who were making their way to work.

"Within a matter of minutes she violently attacked two women and sadly succeeded in murdering one of them.

"For Sally Hodkin her day had started out like any other, she too was making her way into work, when she suffered a violent death at the hands of Nicola Edgington.

"Sally’s family has had to endure the painstaking details of the death of their loved one and they have shown great dignity during this trial, having attended court every day.

"Sally’s death has understandably had a huge effect on her family and I hope that today’s verdict will help in some small way to alleviate some of their heartache.

"This case has been a complex one and my team of officers has worked tirelessly to piece together what happened that day.

"We were greatly assisted by CCTV from the surrounding streets and the picture that emerged was a deeply shocking one.

"I would like to personally thank the witnesses who came forward to help us with this case as their assistance has helped us to secure today’s verdict and hopefully this will brining some form of closure for those affected."