The Metropolitan Police has launched a murder investigation following the death of a baby girl, who was aged just 16 months.
The baby, from the E13 area of east London, was admitted to an east London hospital after falling ill on Friday, 13 September.
She died in hospital on Tuesday, 17 September.
Officers know the identity of the child, but she is not being named at this stage.
A post-mortem examination held on Monday, 23 September at Great Ormond Street Hospital gave the cause of death as a head injury, pending further tests.
A 36-year-old man was arrested on Saturday, 14 September initially on suspicion of causing grievous bodily harm.
He has been released on bail to return in mid-October.