The man found dead alongside his two children and sister-in-law had called police 75 minutes earlier saying he was "confused", it has been revealed.
Bartlomiej Kuczynski, 45, called 999 with concerns about his mental state but police were not sent to the family home in Costessey.
His body and those of his daughters Jasmin, 12, and Natasha, nine, and Kanticha Sukpengpanao, 36, were discovered an hour and 15 minutes later at the property on Allan Bedford Crescent, on the Queen's Hills estate.
The details of his plea for help emerged after the Independent Office for Police Conduct (IOPC) began investigations into Norfolk Constabulary's handling of both the 999 call and its officers' actions after Mr Kuczynski went missing on December 14.
IOPC regional director Charmaine Arbouin said police had received the 999 call shortly before 6am on Friday.
READ MORE: Everything we know so far about the Costessey deaths
“During that call the man expressed concerns for his own mental state saying he was confused. He was advised to seek medical advice and police did not attend,” she said.
“At around 7am the force received a call from a dog walker concerned for the welfare of those within the home.
“Officers attended shortly after and, tragically, found the man, a woman and two children dead.”
Post-mortem examinations found Mr Kuczynski died of a stab wound to the neck while Ms Sukpengpanao died of a number of stab wounds to the neck.
The bodies of the two girls will be examined on Wednesday.
READ MORE: Probe focuses on days leading up to Costessey quadruple death tragedy
It is understood that Mr Kuczynski’s wife Nanthaka had been at home with her family during the night before the tragedy.
She went to work at the Norfolk and Norwich University Hospital early on Friday morning with neighbours reporting having seen her de-ice her car before leaving.
She is believed to have returned home from work at some point on Friday morning but it is not clear at what time.
Her sister had been living at the family’s home after travelling from Thailand to support Nanthaka and her daughters in December, as Mr Kuczynski was suffering from mental health problems.
Neighbours said he had been struggling with mental ill health for several months, for which he had been asking for help.
His disappearance in the run-up to Christmas had prompted a police search of the surrounding area before he was found safe.
Officers took him to the Norfolk and Norwich Hospital for a mental health assessment, but he is understood to have left before this could be carried out.
READ MORE: Police to be held to account after four deaths in Norwich
The IOPC has said its investigation will be examining if the police handling of the contact they had with him was “appropriate and in line with force policy, training and procedures”.
On Monday, chief constable Paul Sanford asked His Majesty’s Inspectorate of Constabulary and Fire and Rescue Services, which is already carrying out a routine inspection of Norfolk police, to conduct a “deeper review”.
The force has also said it is reviewing the introduction of a controversial plan that would see them not attending some 999 mental health calls
The phased introduction of the scheme called Right Person, Right Care, which aims to reduce the amount of time the police devote to mental health-related jobs, is due to start next month but is now “under review”.
Meanwhile, the Norfolk and Suffolk NHS Foundation Trust, which provides mental health services, is coming under growing pressure to provide details of what, if any, care it had been providing to Mr Kuczynski.
The tragedy has stunned those living in and around the Queen's Hills estate with an outpouring of tributes.
READ MORE: 'Cheeky' 12-year-old found in Norwich home deaths was 'always smiling'
Dr Roger Harris, headteacher of Taverham High, paid tribute to Jasmin, who was a pupil at the school, recalling her as “always smiling and even a bit cheeky at times, but as parents, you'd be very proud to call her your daughter”.
Her younger sister, Natasha, attended Queen's Hill Primary School.
Head teacher Matthew Cross, said: "Natasha approached her learning with pride and curiosity while enjoying coming to school, spending time with her friends and making them laugh.
"Her friends, our staff and all of our school community will miss her."
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