More investigations are needed to determine how a five year-old boy died near Bridgend.
The body of Logan Mwangi was found in the River Ogmore near Pandy Park in July.
His stepfather is accused of murder, and his mother has been charged with perverting the course of justice.
But an inquest in Pontypridd heard a post-mortem examination did not establish the provisional cause of death.
The hearing was adjourned until the end of criminal proceedings.
The court heard Logan, also known as Logan Williamson, had been reported missing from home by his parents.
Rachel Knight, the assistant coroner for South Wales Central, said: ''There is reason to expect his death maybe violent or unnatural.''
The post-mortem took place at the University Hospital of Wales in Cardiff three days after the body was found. It had to be identified by Logan's grandmother.
Three people have been charged in connection with the death.
John Cole (39), from Sarn, is accused of murder and is also charged with perverting the course of justice, along with Angharad Williamson (30), also from Sarn, and a 13 year-old boy who we can't name for legal reasons.
All three remain in custody and are due to appear at Newport Crown Court for a plea hearing in November, before going on trial in January.