Police ignored a 999 call from a father who expressed concerns for his own mental state just one hour before he and his two daughters and sister-in-law were found dead at a house near Norwich.
Norfolk Police said the four people have been provisionally identified as Bartolmiej Kuczynski, 45, Jasmin Kuczynska, 12, and nine-year-old Natasha Kuczynska, and their 36-year-old aunt Kanticha Sukpengpanao.
The force have now referred themselves to the Independent Office for Police Conduct after it emerged they had failed to respond to the call made by Mr Kuczynski.
IOPC regional director Charmaine Arbouin said: “Norfolk Constabulary established that the man had made a 999 call to the force shortly before 6am on 19 January.
“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.
An hour later at 7am, a dog walker made a second call to report concerns for the welfare of those inside the property on Allan Bedford Crescent in Costessey.
Upon arrival, officers broke in and discovered the four bodies with a post-mortem examination carried out on Sunday giving Mr Kuczynski and Ms Sukpengpanao’s causes of death as stab wounds to the neck.
The bodies of the two girls will be examined on Wednesday. Detectives leading the investigation have said Mr Kuczynski and his two daughters lived at the address, while his sister-in-law was visiting and lived elsewhere.
The force has also referred itself to the police watchdog over a previous incident at the address on 14 December, which was in relation to a missing person enquiry.
Investigating officers are not looking for anyone else in connection with the four deaths.
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” into his force.
Floral tributes and unicorn toys were left outside the home in the days after the incident, with one mourner writing: “Jasmine, you were such a sweet, caring girl, yourself and your sister didn’t deserve to have your lives taken away.
“You would always be smiling in primary school. Fly high beautiful girls.”
Matthew Cross, headteacher at Queen’s Hill Primary School and Dr Roger Harris at Taverham High School said in a joint statement that extra support was in place for pupils and staff.
“Both our schools have worked closely alongside colleagues from Norfolk County Council’s critical incident support team over the weekend to ensure we have extra support and provision in place so we can meet the needs of both our pupils and staff at this difficult time,” they said.
“Following a mandatory referral from the force we have decided to investigate and will be examining if the force’s handling of the contact they had with the man was appropriate and in line with force policy, training and procedures,” the IOPC said.
“We will be making contact with the families of the deceased to explain our role.
“Our sympathies are with the families and friends of the deceased and all those affected by this incident.”