Police are waiting on further forensic tests from ESR following the sudden death of Raetihi boy Antony Herewini-Christiansen on December 7.
Traces of prescription drugs were found in the 9-year-old's system.
Detective Senior Sergeant Keith Borrell of Taranaki police said the initial test resulted in further, more intricate testing needing to be done.
"So we're waiting on the results of this second test."
Mr Borrell said he was unable to say exactly what prescription drug traces they were looking for but that once these second results were received, they would be able to determine how Antony died.