Post-mortem tests have failed to establish the cause of death of a 15-year-old boy who was found dead in a bath in a flat in Newham, east London.
Police said the boy was found in the flat in Hathaway Crescent, Manor Park, on Christmas Day. He had a "number of injuries", they said.
A Metropolitan Police (Met) spokesman said the Child Abuse Investigation Command was investigating the death.
It is being treated as suspicious, and a man and woman have been arrested.
Officers are now awaiting the results of further tests on the boy's body.
Police were called by London Ambulance Service at about 1215 GMT to reports a boy had drowned. He was pronounced dead at the scene.
The man and a woman, both aged 27, were arrested after the body was found and are being held at separate east London police stations, the Met said.
The force said officers believed they knew the identity of the boy but were awaiting formal identification.
A Met spokesman said: "At this very early stage, this is believed to be a domestic incident.
"Inquiries continue to establish the full circumstances."
Four children found in the flat are under police protection. Two of them were taken to a hospital for treatment after the discovery of the boy's body and later discharged, officers said.
The Met has been given a warrant to detain the arrested pair until Tuesday morning.