Police found the bodies of Bartlomiej Kuczynski, 45, Kanticha Sukpengpanao, 36, Jasmin Kuczynska, 12, and Natasha Kuczynska, eight, at an address in Costessey on 19 January.

Norfolk area coroner Samantha Goward told Wednesday's hearing in Norwich that Natasha's provisional cause of death was recorded as "sharp force injuries to the neck", while Jasmin died of an "incised wound of the neck".

Ms Goward said businesswoman Ms Sukpengpanao, who lived in Thailand, died of "stab wounds to the neck".

She said structural engineer Mr Kuczynski, who was born in Poland, died of a "stab wound to the neck" and a report had been requested from the local mental health trust.

All four of the inquests, opened separately, were adjourned until a pre-inquest review hearing on 29 April.

Norfolk Police said the deaths of Ms Sukpengpanao, Jasmin and Natasha are being treated as murder.

The death of Mr Kuczynski is not being treated as suspicious and officers are not looking for anyone else in connection with the killings, the force said.

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Following the deaths Norfolk Police referred itself to the Independent Office for Police Conduct (IOPC) over prior contact the force had with a man at the property.

IOPC regional director Charmaine Arbouin said an investigation was under way after it emerged that the man made a 999 call to police shortly before 6am on 19 January.

"During that call the man expressed concerns for his own mental state, saying he was confused," she said.

"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."