The review will look into the decision to accept Valdo Calocane's guilty pleas to manslaughter and whether it sufficiently consulted with the families of the victims.

Last week, Calocane was given a hospital order for manslaughter by diminished responsibility after the city's crown court heard he had been diagnosed with paranoid schizophrenia.

The 32-year-old stabbed students Barnaby Webber, 19, Grace O'Malley-Kumar, 19, and school caretaker Ian Coates, 65, with a dagger in the early hours of 13 June last year.

Mr Webber's family described the hospital order as a "huge insult" and called for a public inquiry into the case.

On Tuesday, Attorney General Victoria Prentis said: "The senseless deaths of Barnaby Webber, Grace O'Malley-Kumar and Ian Coates have horrified the country.

"While nothing will bring their loved ones back, the families understandably want to understand what happened in this case.

"That's why I have asked the inspectorate to carry out a prompt and thorough review of CPS actions so we can properly investigate the concerns raised by the families in this devastating case."

Ms Prentis is also considering whether judges should review the sentence after receiving a submission that it could be unduly lenient.

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'We will get answers'

Earlier, Rishi Sunak said independent investigations have been set up into Nottingham institutions' role in alleged missed opportunities to stop Calocane.

It came a day after a meeting with the families of Mr Webber and Ms O'Malley-Kumar in Downing Street.

Mr Sunak said the NHS, police forces and CPS will all be looked at "promptly and thoroughly and effectively" to try and get answers for the families.

Speaking on ITV's This Morning the prime minister said: "What I said to them (the victims' relatives) is that we will get the answers. That's what they deserve. That's what I've committed to.

"Once we hear back from that, then we can sit down with them and decide if there are more questions that need answering, is the inquiry then the next logical step?"

Concerns arose after it emerged an arrest warrant had been issued for Calocane months before the killings.

Leicestershire Police have referred themselves to the Independent Office for Police Conduct (IOPC) and leaders at Nottinghamshire Police have met with Policing Minister Chris Philp.

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Families united in 'national tragedy'

The families of Mr Webber, Mr Coates and Ms O'Malley-Kumar said they welcome the "full, open and transparent investigation" into the CPS.

In a joint statement, they said: "We reiterate our deep and grave concerns in this case, and our disappointment that we have had to resort to this additional level of trauma and stress to feel listened to and for further actions to be taken.

"We are united as families in this national tragedy."

They said they wish to be given the opportunity to speak in person with the IOPC and attorney general about concerns and evidence of concerns that they have.

The findings of the review are expected by Easter.

A spokesperson for His Majesty's Chief Inspector of the CPS said they accept the request for the review.