The 35-year-old woman was allegedly sitting in a her kitchen chanting verses of the Koran as her daughter's disembowelled corpse lay next to her.
The little girl's heart and other organs were found in different rooms around the flat in Clapton, east London.
The woman, believed to be from Somalia, had her MP3 on full blast as she listened to the Muslim holy book.
Shayna Bharuchi, 35, was allegedly sitting in a her kitchen chanting verses of the Koran as her daughter Nusayba's disembowelled corpse lay next to her.
The mother, who is understood to have two teenage children of 14 and 16, has since been sectioned under the Mental Health Act and is in a secure unit as police yesterday continued to guard the third-floor premises on the estate.
The gruesome scene was discovered by the girl's father, Jerome Negney, when he arrived home to the flat on Thursday to find his partner clutching a kitchen knife.
The man, believed to be a Muslim convert, dialled 999 and paramedics pronounced the girl dead at the scene. Police said next of kin have been informed.
One elderly neighbour said last night: 'Nobody knew her very well but the children seemed very nice. However I used to be awoken by terrible screaming of a woman's voice in the middle of the night which was a regular occurence.
'Sometimes the screams would last for about 10 minutes.'
Another neighbour, who lives in the downstairs flat and asked not to be named, said: 'I was feeding my daughter her lunch at about 3pm and suddenly heard horrific screaming. It is shocking and so upsetting.'
He said the couple have lived in the flat for about a year.
A post-mortem examination will take place on Saturday at Poplar mortuary in east London.
The Metropolitan Police's Child Abuse Investigation Command is leading the murder inquiry. They are not believed to be looking for anybody else.