A five-year-old girl discovered dead with her sister and mother had been strangled, a post-mortem examination has shown.
A concerned relative alerted police
Anika Khanum was found on Wednesday with six-year-old Thanha, who had suffered a head injury. It is not yet known how mother Juli Begum, 26, died.
Their bodies were found at a house in Nelson Street, East Ham, east London.
A triple murder inquiry has begun and detectives have appealed to the Bangladeshi community for information.
Officers have confirmed there were no signs of forced entry to the property.
A neighbour said the dead woman's sister visited him on Tuesday after failing to hear from her for nine days.
The pair of them got no response at the house and were struck by how cold it was, so decided to contact police.
Another neighbour who lived along the same street described the woman living at the house as "very pleasant but quiet".
Further post-mortem examinations are to be carried out on Ms Begum.