Detectives investigating the house fire in Harlow that killed a woman and all five of her children, are now treating the deaths as murder.
The blaze was started by burglars in the lounge, and the flames then spread throughout the house.
There is a £10,000 reward to help catch the killers.
Lauren Hall reports.
Essex police say they've received a number of calls after a TV appeal over the house fire that killed a family of six in Harlow.
Dr Sabah Usmani and her five children died after the blaze last month. It's now being treated as murder.
In a fresh appeal on the BBC's crimewatch programme last night, police asked for information about a laptop stolen from the house on the night of the fire. Detectives described the case as tragic and unprecedented for the force.
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A spokesman for Essex Police said:
"Evidence from fire scientists has indicated that the likely cause of the fire was malicious ignition.
"Detectives know that there was a burglary at the house on the same evening/early morning of the fire and are re-appealing for information and witnesses."
A house fire that killed a mother and her five children in Harlow, Essex, last month is now being treated as a murder investigation, Essex Police said tonight.
Crimestoppers have said it would pay the reward for information leading to the arrest and conviction of those responsible.
– Ann Scott, the Crimestoppers' eastern regional manager
This is an absolutely heartbreaking incident which has devastated and shocked the entire community.
It is impossible to imagine how Dr Shakoor, who survived the fire, is coping with the loss of his family.
Please come forward to the independent charity Crimestoppers so this truly awful crime can be solved.
Ann Scott added that people had "nothing to fear" by contacting Crimestoppers as all witnesses could remain anonymous.
A £10,000 reward is being offered for information on an Essex house fire that killed a mother and her five children.
The blaze killed Sabah Usmani, her daughters Hira and Maheen and her sons Sohaib, Muneeb and Rayyan in Harlow last month.
Police are keen for information on a group of young men seen outside the house on the night of the fire.
Police in Essex are speaking to two young people, seen throwing away a laptop bag on the night of a fatal fire.
It's been revealed the house in Harlow - where Sabah Usmani and her five children died - was burgled on the night of the blaze.
Officers think several items, including a laptop, were taken after the family had gone to bed but before the fire was discovered.
Police reveal the home, where a mother and her five children were killed in a fire, was burgled on the night they died.
Sabah Usmani and her children were all killed after flames swept through their home in Harlow in Essex last month.
The children's father survived.
Police have said his laptop bag was discovered abandoned, two weeks after the fire.
Ria Chatterjee reports on the latest developments in the investigation.
– DETECTIVE SUPERINTENDENT ROB VINSON
We urgently need to speak to these two young people about where they found the bag.
Dr Shakoor remembers leaving his Toshiba Satellite laptop in the lounge when he went to bed that evening.
The fire that raged through the downstairs of the house has left the contents totally destroyed.
We now believe that this laptop may have been stolen.
Recent developments have moved the investigation forward in a number of directions and we now believe that there was a burglary at Dr Shakoor's house in Barn Mead in which items were removed from the house.
We believe that this burglary took place after the family had gone to bed and before the fire was discovered.
– Detective Superintendent Rob Vinson
Our inquiries have revealed that in Harlow during the same evening and early morning there were two other unsuccessful attempts to break in to other properties and one where entry was gained but the suspect was disturbed and nothing was taken.
How these incidents relate to the current investigation is ongoing.