Investigators are probing whether chances were missed to give mental health support to a man who was found dead alongside three members of his family.
The body of Bartlomiej Kuczynski, his two young daughters and his sister-in-law were discovered by police at his property in Queen's Hills, on the outskirts of Norwich, on Friday morning.
But shortly before Christmas, Mr Kuczynski had been reported as missing, sparking a police search of woodlands near Costessey which included the use of drones.
Neighbours say he was eventually located on the Fairway, on the Queen's Hills estate close to his home.
The incident is believed to have been prompted by concerns for Mr Kuczynski's mental wellbeing.
It is understood that officers took him to the Norfolk and Norwich University Hospital for assessment, but that he left the Colney site unescorted before this could be carried out.
This incident on December 14 - along with a 999 call he made from his house on Friday morning just an hour before the gruesome discovery - is at the centre of an investigation by the Independent Office for Police Conduct (IOPC).
Norfolk Constabulary confirmed over the weekend that it had referred itself to the watchdog over its handling of the incidents.
The IOPC investigations will look at whether police responded appropriately to both incidents, while wider inquiries are also expected to explore whether any opportunities were missed to ensure mental health support was made available to him on December 14.
Neighbours said the 45-year-old had been struggling with mental ill health for several months, for which he had been asking for help.
However, it is not clear how much engagement he had with mental health services before he went missing in December - if any.
The Norfolk and Suffolk NHS Foundation Trust, which is responsible for specialist mental health care in the region, said it could not comment due to the ongoing police investigations.
The Norfolk and Norwich University Hospital was also unable to provide comment for the same reason.
The tragedy was discovered at 7.15am on Friday morning after a neighbour alerted police to a disturbance.
Officers gained entry to the home in Allan Bedford Crescent where they discovered the bodies of Mr Kuczynski, his 12-year-old daughter Jasmin and her seven-year-old sister, Downreuang.
The body of Kanticha Noon, 36, the girls' maternal aunt, was also found inside the home.
According to reports, Ms Noon was on a trip from Thailand to visit her sister's family and had arrived in the UK on December 27. She previously visited the family in June.
She was staying at the house in Costessey and was due to return home at some point next month.
Her sister, Mr Kuczynski's wife, was understood to be at work at the hospital when the deaths were discovered.
Post-mortem examinations conducted over the weekend revealed that Mr Kuczynski had died from a single stab wound to the neck - while Ms Noon died from multiple stab wounds to the neck.
Examinations are yet to be conducted on the bodies of the girls, who attended Taverham High School and Queen's Hill Primary respectively.
At around 6am on the Friday, police received a 999 call from inside the property, understood to have been made by Mr Kuczynski himself.
The contents of the phone call are not known at this stage, but officers did not attend the address until the subsequent call from the neighbour was made an hour later.
The tragedy comes at a time when Norfolk Constabulary is in the process of a phased introduction of a scheme called Right Person, Right Care, which aims to reduce the amount of time the force devotes to mental health-related jobs.
Throughout the consideration of this scheme, campaigners have voiced concerns that this could put people in crisis more at risk.
But the force has always maintained it would still attend situations involving mental health where there is judged to be an immediate threat to life.
The scheme was due to be introduced from next month, but has since been paused.
Giles Orpen-Smellie, Norfolk's police and crime commissioner, has pledged to "robustly" hold the county's chief constable account for the actions of officers and staff.
He said people in Norfolk "must be able to depend on the effective working of the 999 system".
Meanwhile, floral tributes continue to be left near the family home, with support being offered to children at the two schools where the girls were pupils, Queen’s Hill Primary School and Taverham High School.
In a joint statement, their respective headteachers, Matthew Cross and Dr Roger Harris, said: “We have extra support and provision in place so we can meet the needs of both our pupils and staff at this difficult time."
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