By Lisa Dowd, Midlands Correspondent
An NHS Trust has admitted it has "lessons to learn" after a paranoid schizophrenic was detained indefinitely for killing schoolgirl Christina Edkins.
Philip Simelane stabbed the 16-year-old in a random attack on a bus during the rush hour less than three months after he was released unsupervised from prison, despite warnings over the state of his mental health.
Simelane, 23, who has a history of mental illness, was sentenced at Birmingham Crown Court after admitting manslaughter on the grounds of diminished responsibility.
Birmingham and Solihull Mental Health NHS Foundation Trust said it was leading an external review into the case as Christina's family asked questions about Simelane's treatment.
The court heard that before the killing a specialist registrar had recommended Simelane should receive specialist in-patient treatment for his mental health issues.
It also emerged that a year before the fatal stabbing he had made death threats on a bus to two girls, who warned the authorities that he may have been mentally ill.
Mrs Justice Thirlwall said anyone hearing the facts of the case would be disturbed that Simelane was sleeping rough and receiving no treatment when he attacked Christina in Birmingham in March.
The judge said that as early as mid-2005, his own mother was "repeatedly asking for help" for her son and was desperate for assistance.
In July last year he was made the subject of a restraining order and jailed for 26 weeks for offences, including an assault on a police officer and an incident in which he threatened his mother with a knife.
Christina's family arrive at Birmingham Crown Court
But a week after his release from prison in October 2012, Simelane was jailed again for vehicle interference.
The judge said he finally received some treatment in prison but it was limited and an investigation will try to establish why that did not apparently continue after his release in December 2012.
Brian Russell, defending, told the court he had asked Simelane before the hearing if he had anything to say to those who had been affected by the killing.
"He said 'I didn't mean to kill that girl, I am ashamed of what has happened and I wish to apologise'."
A family statement issued after the guilty plea said: "Christina was a beautiful, bright, caring girl, loved by everyone.
"The loss of a child is the worst thing that can ever happen, made even more grievous be such a senseless crime as this.
"The family are all the victims and must pay the penalty as we stand by helplessly and watch the lives of the people we love shattered like precious glass, knowing we can never put the fragile pieces back together."
Christina's great uncle, Chris Melia, told Sky News: "It's such a horrific senseless crime. I don't know how you come to terms with it. I haven't."
"He quite clearly shouldn't have been out in society, there had been enough warning signs that he was a danger.
Jason Edkins, Christina's father
"As I understand it, in October, whilst he was in prison, the appropriate mental health experts noted he should, when he was released, be in some way supervised and helped to get back into society in an acceptable manner, but it didn't happen.
"He was released on 13th December, basically with no fixed abode, and in less than three months he killed an innocent young girl in the prime of her life."
Mr Melia paid tribute to Christina as a "popular", "attractive" and "quietly confident" girl.
The Birmingham and Solihull Mental Health NHS Foundation Trust confirmed it was involved in Simelane's prison-based care.
In a statement, the trust said: "We would like to offer our sincere condolences to Christina's family for what was an unprovoked attack on an innocent member of the public.
"Phillip Simelane had previously been in receipt of care from a number of healthcare providers over a period of years.
"What is clear, is that there are lessons to be learned for us and others involved in the care of Phillip Simelane to prevent such a tragedy happening again in the future.
"As a trust we are currently leading an external review, commissioned by Birmingham Cross City Clinical Commissioning Group, on behalf of all the parties involved and intend to report on our findings in December 2013.
"We would not want to speculate on the outcome of this review, but we are clear that this will be an externally reviewed, thorough investigation and we will seek to learn from and fully implement these findings across the healthcare providers involved."
Christina was preparing to take her GCSEs when she died
West Midlands Police say they were called to Simelane's home in Walsall by his family 21 times. On one occasion he held a knife to his mother's stomach.
Superintendent Richard Baker said: "There doesn't appear to be any care plan since his release from prison in December 2012.
"There's currently an independent review being conducted by all agencies who had contact with Phillip Simelane during that period, not just police but probation, prison, and Birmingham and Solihull mental health team will also conduct independent reviews to understand exactly what support Simelane had in place."
He added it was "highly unlikely" that Simelane would ever be released.
Simelane, who was homeless, boarded the number 9 bus at 5am on March 7. He had been challenged by the driver for sleeping on the back seat on the top deck.
Christina got on the bus at 7.30am on the city's Broad Street, a journey she made every day. Seven minutes later, she was dead.
Without warning, and for no reason, Simelane got up and thrust a kitchen knife into her chest once. He then casually walked down the aisle, down the stairs, and briefly spoke to the driver before getting off.
There was just one other passenger upstairs, a 14-year-old boy, who only realised what had happened when Christina cried out for help. Downstairs passengers rushed to her aid, but she could not be saved.
Officers scoured the city centre for Simelane and arrested him more than four hours later.