The sentence of Nottingham knifeman Valdo Calocane has raised questions about what other options could be available if Court of Appeal judges did reconsider the case.

Labour leader Sir Keir Starmer added his voice to calls for an inquiry into any failings that led to the attacks after the families of the three people Calocane killed reacted angrily to the sentencing, accusing prosecutors of a “fait accompli” in accepting a guilty plea to manslaughter by diminished responsibility rather than pursuing murder charges.

Judge Mr Justice Turner said Calocane would “very probably” be detained in a high-security hospital for the rest of his life as he sentenced him to a hospital order for the “atrocious” killings, as well as the attempted murder of three others.

The Attorney General Victoria Prentis is now considering whether senior judges should review Calocane’s sentence after receiving a submission that it could be unduly lenient.

Under the scheme which allows any person or institution to ask for a sentence to be reviewed, the Cabinet minister has 28 days from sentencing to consider the request and decide whether to refer the case to the Court of Appeal to rule on whether the sentence was appropriate.

With a hospital order in place, this poses questions as to what other sentences could be available if Court of Appeal judges were asked to consider the case.

The complex arrangements are essentially a direction for treatment rather than seen as a penal punishment and, as such, it is not entirely clear at this stage how judges could increase the sentence to make it more stringent.

Judge Mr Justice Turner made a hospital order for Calocane to be re-admitted and detained at Ashworth High Security Hospital, near Liverpool, under sections 37 and 41 of the Mental Health Act 1983.

It means Calocane will be detained in a psychiatric hospital for treatment and will not be discharged until he is deemed well enough and either the Justice Secretary or a Mental Health Tribunal assess that he no longer poses a risk to the public.

During sentencing, the judge said he was “entirely satisfied on the evidence, in the particular circumstances of this case and for the reasons I have given” that this was the “proper sentence” to impose.

The Attorney General’s considerations are unlikely to look at whether the correct charge was pursued in Calocane’s case, the PA news agency understands.

Another sentencing option is to reconsider whether it is appropriate for Calocane to spend some time in jail for his crimes, if he was ever deemed suitable for discharge from hospital.

But, during sentencing, Judge Mr Justice Turner set out his reasons as to why a 45A hospital order – known as a hybrid order as it imposes a prison sentence and directs admission to hospital – would not be appropriate.

He said there were “significant concerns” that if Calocane relapsed in prison he “would present a real danger to prison officers and fellow prisoners alike”.

It came after psychiatrist Dr Nigel Blackwood warned the court imposing a hybrid order could lead Calocane – who has a treatment-resistant form of paranoid schizophrenia – to stop taking medication while in jail which would carry a “significant risk of lethal behaviours returning”.

If Calocane did go to prison, and in the “unlikely event” he was ever released, the judge said he needed to consider which regime would “provide the greatest level of protection for the public” and raised concerns that he would not be supervised by mental health experts post jail.

Instead, on release from prison, he would be monitored by probation officers who would lack sufficient training and knowledge to spot the warning signs of deteriorating behaviour as well as not having the powers to intervene and arrest him if required, the judge added.

If the case is referred to the Court of Appeal, judges could also rule the sentence should remain the same, or decide to refuse to hear the case altogether.