A mentally ill man has been detained indefinitely for stabbing a schoolgirl to death in a "chilling" knife attack on a bus.
Phillip Simelane killed 16-year-old Christina Edkins in Birmingham in March after being released unsupervised from prison three months earlier despite worries about his mental state.
Ordering Simelane to be detained in a secure psychiatric unit, Mrs Justice Thirlwall expressed concern that the 23-year-old was not receiving treatment at the time of the killing.
Simelane, who was suffering from paranoid schizophrenia, was released from jail in December last year after serving a four-week sentence for vehicle interference.
It emerged today a specialist registrar had earlier recommended Simelane, from Walsall, should receive specialist in-patient treatment for his mental health issues.
But Simelane, who pleaded guilty to manslaughter on the grounds of diminished responsibility, was sleeping on the streets and receiving no treatment when he stabbed Christina in a random attack at about 7.30am on March 7.
The court heard Simelane's mental health problems began in his mid-teens and coincided with several criminal convictions, including two previous offences involving knives.
Passing a hospital order on Simelane, Mrs Justice Thirlwall said anyone hearing the facts of the case would be "disturbed" that he was living in the community with an illness of such severity.
The judge told Simelane: "At the time you attacked Christina you were suffering from a serious mental illness.
"Your mental function was wholly abnormal as a result of your mental illness. That is why you killed Christina - in your deluded state you thought she was a danger to you.
"It is difficult to understand how it came about that in December 2012 someone with your level of illness should have been sleeping rough with no one to look after you."
The judge said: "On at least two occasions an experienced specialist registrar in psychiatry insisted you needed in-patient treatment. It was not made available to you."
Referring to an incident a year before the fatal stabbing in which Simelane made death threats towards two girls on a bus, the judge went on: "Those who gave statements - ordinary lay people - were of the view that you were mentally ill.
"The terrible reality is that Christina was the person who happened to be on the bus on the day you were overwhelmed by your illness."
The judge, addressing an impassive Simelane, said: "You saw Christina get on the bus and CCTV shows in chilling detail you were watching her.
"After a few minutes you walked towards her and stabbed her.
"The blow of the knife penetrated deep in her chest - it took seconds.
"Christina had no chance."
The teenager was travelling to her friend's house en route to Halesowen's Leasowes High School when she was confronted by Simelane, who had been sleeping on the bus since around 5am.
Other passengers did all they could to treat Christina but when paramedics arrived just moments later they found she was not breathing and had no pulse.
Simelane was arrested about four-and-a-half hours after the stabbing in a nearby street.
A police search of the local area led to the recovery of a white bag containing the weapon used to stab Christina, a mobile phone, a smoked joint, and a piece of paper bearing Simelane's fingerprints.
Outlining Simelane's psychiatric history, prosecutor Peter Grieves-Smith said the defendant had been heard making threats against two schoolgirls on a bus around a year before the stabbing.
Born in Swaziland, Simelane received a reprimand for possessing a knife in 2007 when he was aged 17.
Simelane was also cautioned for an offence of battery two years later and given a conditional discharge for criminal damage in May last year.
Other offences, including an assault on a police officer and an incident in which he threatened his mother with a knife, saw Simelane made the subject of a restraining order and jailed for 26 weeks in July last year.
But a week after his release from prison in October 2012, Simelane was jailed again for vehicle interference.
The judge said it was clear Simelane had been suffering a "pervasive and pernicious" form of mental illness at the time of the attack.
She directed a full account of the hearing be made available to the independent inquiry teams now looking into the case.
During her sentencing remarks, Mrs Justice Thirlwall said it was plain from the medical evidence of psychiatric experts that given the severity of Simelane's condition his responsibility was diminished.
She said as early as mid-2005, Simelane's own mother was "repeatedly asking for help" for her son and was desperate for assistance.
In prison he had finally received some treatment but it was limited, the judge added.
"I shall say no more of the history but there is an inquiry being carried out in this case," she said.
"I direct this hearing is transcribed and provided to those carrying out this inquiry."
The judge said the effects of Simelane's shocking actions would stay with the teenager's family for years to come.
After ordering Simelane to be taken down to cells, Mrs Justice Thirlwall turned to address Christina's family, praising the "dignity" with which they had carried themselves throughout.
She told the teenager's mother Kathleen she had been "moved and humbled" by her victim impact statement.
"It paints the whole picture of Christina as a living, breathing, caring and exciting young woman, full of care, concern and generosity.
"I was struck that her headteacher wrote that if a school could choose its pupils it would be full of Christinas."
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'.'"
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."