Calocane, who had been diagnosed with paranoid schizophrenia before he fatally attacked Barnaby Webber, Grace O’Malley-Kumar and Ian Coates in June 2023, was previously sectioned by Nottinghamshire Healthcare NHS Foundation Trust.
A public inquiry, which finished hearing evidence in May, was told he had been discharged in 2022 because he failed to turn up for appointments and the team had «lost» him.
The investigation into the trust is being carried out by Northumbria Police.
Nottinghamshire Police has been criticised over its history of interactions with Calocane and its handling of the response and investigation into the attacks.
A spokesperson for Nottinghamshire Healthcare NHS Foundation Trust said: «Northumbria Police, acting on behalf of Nottinghamshire Police, have begun an investigation into matters relating to the care and treatment of Valdo Calocane.
«We know how important the independent inquiry and police investigation are for the affected families, the survivors and our local communities.
«We will, of course, be co-operating fully with Northumbria Police, as we have with the Statutory Inquiry into these matters which is being chaired by Her Honour Deborah Taylor, and which will hear final submissions from all the parties involved later this year.»
Nottinghamshire PoliceNottinghamshire Healthcare was responsible for Calocane’s care for two years before he was discharged in September 2022.
He was sectioned under the Mental Health Act four times during that two-year period and warned by a doctor he would end up killing somebody.
Following the attacks, he pleaded guilty to three counts of manslaughter, on the grounds of diminished responsibility, and to three counts of attempted murder.
Calocane is currently serving an indefinite hospital order in a high-security facility.
The Nottingham Inquiry, which heard evidence from doctors, nurses and other NHS staff, was told there had been numerous errors in Calocane’s care and management.
He had a history of non-compliance with his medication and was known to become violent when he was unwell, it heard.
One of the key themes in the evidence about the killer’s care under the Nottinghamshire trust was that his risk to others was not properly assessed or managed.
The trust had already been under the close scrutiny of the health and social care watchdog, the Care Quality Commission (CQC) before Calocane was under its care.
In October 2021, an email to staff said the trust had reached a point where services were «not safe», with concerns raised about staffing levels.
By then, Calocane had been sectioned three times.