A man and a woman found dead along with two girls at a house in Norfolk both died from stab wounds to the neck, police said.
Officers discovered the bodies of 45-year-old Bartlomiej Kuczynski and two girls – thought to be his two young daughters – after forcing their way into the property in Allan Bedford Crescent, Costessey, near Norwich, on Friday morning.
The body of a 36-year-old woman, said to be part of the same family, was discovered alongside them.
Norfolk Police said all four had injuries and detectives are not looking for anyone else in connection with the incident.
The force has referred itself to the police watchdog after revealing an emergency 999 call was earlier made by a man from the address, but officers failed to respond.
Police said post-mortem examinations found the woman died from stab wounds to the neck, while the man died from a stab wound to the neck.
Post-mortem examinations on the two girls are due to be carried out on Wednesday.
Detective Chief Inspector Chris Burgess, who is leading the investigation, said: “Following this latest development we remain satisfied no one else was involved in this incident.
“This latest information will only add to the distress and shock felt by members of the local community and it’s why, from the outset, we’ve been determined to carry out detailed and methodical enquiries to make sure we fully understand how this incident has happened.”
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Nina Crisan, whose son knew one of the girls, named Jasmin, described her as a “very, very sweet girl”.
“She had very calm and cool energy, as my son would say,” she told Sky News. “She was just a lovely, lovely, lovely kid.”
She said the incident had come as an “absolute shock” to those who lived in the area.
“[It’s just] absolute shock, absolute shock and devastation.
“This is a really close community. And we all, even if we don’t know each other directly, sort of know each other through, the children, or through dog walking.”
An emergency 999 call was made from the address at around 6am, by a man, but police failed to respond.
Officers later forced their way into the property after being alerted by a member of the public, who was concerned for the welfare of the people inside, shortly before 7am.
The Norfolk force has referred itself to the Independent Office of Police Conduct (IOPC) watchdog in relation to the 6am call, “to which police resources were not deployed”.
Police had already contacted the IOPC over the incident because officers attended the property on 14 December last year in relation to a missing person inquiry.