An inquest into the death of a woman and her five children in a fire in Harlow has heard from a Detective who said, he believes they were murdered.

Dr Sabah Usmani, 44, her sons Muneeb, nine, and Rayyan, six, and daughter Hira, 12, died soon after the blaze in Barn Mead, Harlow, Essex, which police believe was started deliberately in the early hours of October 15, 2012.

A third son Sohaib, 11, and daughter Maheen, three, were taken to hospital. He died later that morning while she lived for three more days.

The only survivor, Dr Abdul Shakoor, who fought hard to save his wife and children, attended the inquest at Essex Coroner's Court in Chelmsford today.

Chelmsford Coroner's court.

Dr Abdul Shakoor (left) arriving at Chelmsford Coroner's court.

Experts told the hearing that the heat of the fire may have reached 800C.

Although the inquest heard that the blaze was most likely started deliberately, coroner Caroline Beasley Murray said there was not enough evidence for her to conclude that the deaths were definitely the result of unlawful killing or an accident. She recorded an open verdict.

She added: "In order to record a conclusion of unlawful killing I would have to be sure that somebody killed another without legal justification and intended to kill or cause serious injury.

"The court has come to the view that, sadly, there is also insufficient evidence to say it was an accident.

"I am recording an open verdict; this basically means that not all of the pieces of the jigsaw are there yet."

Referring to Maheen, she said: "I'm sure all of us were touched by the evidence that her mother was doing her best to protect her at the end.

"The actions of firefighters were nothing short of heroic and the court would like publicly to thank them."

Retired fire investigation officer David Hajicostas said Dr Usmani was found crouched over Maheen in a desperate bid to save her - an act which gave the girl three further days of life and a chance of survival.

David Hajicostas, Retired fire investigation officer (left).

She was gathered over her on all fours with a blanket over her. David Hajicostas, Retired fire investigation officer

He described the actions of firefighters as heroic.

"One officer went back into the burning inferno four times and recovered four people," he said.

"It was between 700C and 800C inside the house at the time of rescue."

The house in Harlow.

Inside the house in Harlow.

Fire investigators found that the blaze was most likely caused by a deliberate act, although it was possible that there had been an accident.Forensic fire specialist Iain Peck, who also examined a car blaze outside the house, said the incidents were likely to be linked.

He added: "These were contemporaneous and linked events - they were separate ignitions but not a coincidence."

Aerial shot of the house in Barn Mead.

Detective Superintendent Rob Vinson gave evidence.

Detective Superintendent Rob Vinson, of Essex Police, said all the evidence pointed towards the deaths being murder.

The front door of the house was open, a laptop was missing and there had been a series of burglaries in the area that night.

Mr Vinson said that although nobody has been charged, it remains an active investigation.

"It's the largest and most complex investigation that Essex Police has ever undertaken," he said.

Flowers laid at the scene to remember the family that died.

All members of the family, originally from Pakistan, died from their injuries and inhalation of fumes, a post-mortem examination found.