A house in Essex where a doctor and her five children died in a fire may have been burgled, the police have said.
Sabah Usmani and the children died after a fire at their home in Barn Mead, Harlow, in the early hours of October 15.
Her husband, Abdul Shakoor, who is also a doctor, tried unsuccessfully to save his family from the blaze.
Detectives from the Kent and Essex Serious Crime Directorate believe there may have been a burglary at the home after the family went to bed and before the fire was discovered.
A laptop bag containing personal papers belonging to Dr Shakoor was found abandoned near lock-up garages in Whitewaits, Harlow, on October 26, and police believe the laptop may have been stolen in the burglary.
Police said that on October 15 there were two unsuccessful attempts to break into other properties in Harlow.
Detectives are investigating if these incidents relate to the suspected burglary at the family's house.
Police officers and Dr Shakoor have asked members of the public with information to come forward.
Two people, a teenage boy aged 15 to 16 who was wearing a tracksuit, and a slim girl in a Burnt Mill School uniform, were seen throwing the laptop bag away near the garages in Whitewaits.
Police said: "Detectives need to speak to them urgently to find out where they found the bag (and are) also appealing for information about the whereabouts of Dr Shakoor's Toshiba laptop."
"Dr Shakoor remembers leaving the laptop in the living room before going to bed on the evening of the fire.
"It was bought in Saudi Arabia and has a two-pin connection that was used with an adaptor.
"Officers are asking anyone who has been offered a second-hand laptop to come forward."
Police also want to speak to a group of four young men who were outside the house in the early hours of October 15.
The young men - aged between 16 and 19 - were wearing tracksuits and baseball caps. There were also two boys on bikes.
Emergency services fought to save the family during the blaze, but Sabah, a 44-year-old doctor, her daughter Hira, 12, and sons Sohaib, 11, and Rayyan, six, died at the scene.
Her son Muneeb, nine, and daughter Maheen, three, were taken to hospital in a critical condition and later died.
Essex Police and the Fire and Rescue Service, along with independent fire experts, have so far been unable to identify the cause of the blaze.
Detective Superintendent Rob Vinson said: "From the onset this house fire and that of the nearby car fire were investigated as suspicious incidents by a dedicated team from the Kent and Essex Serious Crime Directorate.
"Scientists have been sifting through the remains of the fire and have confirmed that to date there is no evidence of a flammable liquid being used. It is however important to emphasise that detailed forensic testing remains ongoing.
"Behind the scenes detectives and specially trained staff have been working around the clock piecing together information and intelligence which has led us to this point.
"This remains one of the most complex cases the investigative team has ever dealt with, but we remain steadfast in our approach and confident the answers lie within the local community.
"We will continue to gain intelligence and work to find answers to the questions of what happened that resulted in such a tragic loss of life."
Dr Shakoor has pleaded with members of the public with information that could help detectives to come forward.
He said: "It is impossible for me to put into words what the loss of my wife and children means to me and the devastating effect it has had on all of my family.
"In the space of just one night I have lost everything dearest to me. Today I am looking to the community once again for help in providing answers to the many questions that remain."