The inquiry into the sudden death of Cobden toddler Leith Hutchison, who died in April, is ongoing as police await forensic test results from overseas.
The 15-month-old died in Starship Hospital in Auckland, two days after he was rushed to Grey Base Hospital suffering cardiac arrest and not breathing.
Following the death, Greymouth police said they were considering the possibility Leith had suffered an assault some time prior to his being taken to hospital.
Tests being conducted overseas following the post-mortem examination would confirm whether the little boy had suffered a brain injury.
West Coast police area commander Inspector John Canning said the test results were still expected to take some time. In the interim, police were conducting a lot of background "spadework" collating all the information they had gathered so far to build a case, he said.
