A father found dead at his family home alongside his two daughters and sister-in-law had told police an hour earlier that he feared for his “mental state”.
Bartlomiej Kuczynski, a 45-year-old Polish engineer, phoned 999 at 6am on Jan 19 in a state of confusion and asking for help, the police watchdog disclosed on Tuesday.
But Norfolk Constabulary simply told him to take medical advice.
An hour later, officers found his body and those of his daughters, Jasmin, 12, and Natasha, nine, and their aunt Kanticha Sukpengpanao, 36, inside their house in Costessey near Norwich.
Post-mortem examinations found Mr Kuczynski died of a single stab wound to the neck while Ms Sukpengpanao died from multiple stab wounds to the neck.
Further examinations on the two girls will be carried out on Wednesday. Detectives have confirmed they are not looking for anyone else in connection with the incident.
The Norfolk force now faces questions from the Independent Office for Police Conduct (IOPC) over whether anything could have been done to avert the tragedy.
It is the second referral the force has made over the case to the watchdog.
It has emerged that officers were called to the family home last month after Mr Kuczynski went missing.
They reportedly searched woodland near his semi-detached house before eventually finding him on the Queen’s Hill estate nearby.
It is understood he was taken to Norfolk and Norwich University Hospital for an assessment, but he left the site in Colney unescorted before it was carried out.
Aunt was ‘nice and caring’
Naty Wathanakul, a close friend of Ms Sukpengpanao, said the aunt had been staying at the family’s home on a visit from Thailand.
She told The Mirror: “She was very nice and caring to all friends of her, a really big supportive person, she helped everyone.
“We have been shocked and depressed since we knew about her death.”
The IOPC said it has launched an investigation to establish the full extent of the contact the Norfolk force had with the family prior to their violent deaths.
Charmaine Arbouin, the watchdog’s regional director, said: “Norfolk Constabulary established that the man had made a 999 call to the force shortly before 6am on Jan 19.
“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.
“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.
“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.
“We will be making contact with the families of the deceased to explain our role.
Police chief asks for ‘deeper review’
“Our sympathies are with the families and friends of the deceased and all those affected by this incident.”
Giles Orpen-Smellie, Norfolk’s Police and Crime Commissioner vowed to “robustly” hold Paul Sanford, the chief constable, to account “for the actions of his officers and staff”.
“I am clear that the residents of Norfolk must be able to depend on the effective working of the 999 system,” he said.
Mr Sanford has asked His Majesty’s Inspectorate of Constabulary and Fire and Rescue Services to conduct a “deeper review” into his force.