A brother and sister who were allegedly killed by their father had been strangled, tests revealed today.
Theo Molemohi, aged two, and Yolanda Molemohi aged four, were found unconscious at their home in Manchester yesterday morning.
A spokesman for Greater Manchester Police (GMP) said: "The cause of death for both children was strangulation."
Their father, 37, was arrested on suspicion of murder and remains in hospital after collapsing in police custody.
Officers described Petros Mwashita's condition as "unwell" but hope to question him later today. Mwashita is also known to use the name Petros Williams.
The children's mother, Morongoe Molemohi, discovered their bodies in the bedroom of the flat in Whalley Road, Whalley Range. Police said their father was with them.
Detective Superintendent Geoff Wessell, of GMP, said the parents were recently estranged.
It is understood that the Zimbabwean couple had separated and Ms Molemohi had moved out of their ground floor housing association flat and been living in bed and breakfasts as well as homeless shelters.
Mr Wessell said the children spent the weekend with their father and their mother had gone to the flat to pick up some of her belongings when she made the grim discovery.
Mr Wessell said: "They were found in a bedroom with the father there next to them. He lived at the address. His ex-partner recently moved out and had agreed to let the father look after the children for the weekend.
"She had gone back for clothes and let herself in and was confronted by this traumatic scene."
Mr Wessell said detectives were not seeking anyone else in connection with the deaths.
The family has lived in England for six years. It is believed that Ms Molemohi was studying for a PhD and her husband was unemployed.
Flowers and teddy bears were left outside the block of flats today. One home-made card in the shape of a daisy had a photo of the two deceased children on it.
Two white teddy bears and a grey teddy bear wearing a crucifix were also left.
Several mothers who had dropped their children off at the local primary school attended by Yolanda stopped to look at the tributes and clutched each other tightly.
Police officers patrolled outside the gates of Our Lady's RC Primary School, whose teachers described Yolanda as a "lovely, happy, bubbly little girl".
Neighbours yesterday described the children as "happy and well cared-for" and said they were often seen playing in the communal gardens.