A Bradford mum was "100 per cent sure" that her three-year-old son had suffocated his baby sister, an inquest into the tot's death has heard.
Four-month-old Hawwa Hanifa Khan was not breathing when her mum Mariyah Fatima found her in a cot on March 16, 2011.
The inquest in Bradford heard that just before finding Hawwa, Mrs Fatima had finished a 38-minute phone call downstairs at their home on Estcourt Road, Lidget Green.
Hawwa's older brother was also found in the cot, the inquest was told. He had been downstairs watching television when Mrs Fatima started her phone call.
Dr Charles Wilson, a forensic pathologist, told the inquest today that Hawwa suffered a heart attack but was resuscitated from the "point of death" by a paramedic. The hearing was told that Hawwa was taken to Bradford Royal Infirmary and later transferred to Leeds General Infirmary, but died on March 24, 2011.
Dr Wilson gave her cause of death as "severe damage to her brain caused by starvation of blood and oxygen". He said the most likely cause of it all was the obstruction of Hawwa's airway.
After Dr Wilson gave his evidence, Mrs Fatima told the inquest: "I want my little boy out of the picture. He is seven-years-old now.
"Only God knows what happened that day. I don't want my little boy having the slightest doubt that anything might have happened."
Dr Wilson, who said there was no evidence of infection, trauma or natural disease, added: "Sadly, I simply cannot tell you precisely how your little girl died. It is unexplained."
Mrs Fatima added: "I jumped to conclusions at the time. My little boy was out of control at that time. I don't hold him to account.
"I told myself over and over again that he had nothing to do with it and she happened to be like that when he got in the cot, that he just happened to be in the wrong place at the wrong time."
The hearing heard a statement from Dr Christopher Smith, a consultant paediatrician who was called to see Hawwa in hospital in relation to child protection issues.
Referring to Mrs Fatima, he said: "She was absolutely 100 per cent sure Hawwa had been suffocated by her son. But she did not see at any stage her son in contact with Hawwa - only that her son was in the same cot."
He added: "I do not think it is possible her son would hold something over Hawwa's airway long enough for her heart to stop.
The inquest also heard a statement from paramedic Sheryl Davies, which included mention of a "milk and blood frothy-type liquid round the baby's mouth", when she attended the house.
Detective Superintendent Simon Atkinson, of West Yorkshire Police, told the inquest an investigation found that no criminal offences had been committed.
The inquest continues.