Probe into NSW baby's death continues

NSW Police are continuing to investigate the death of a two-month-old boy who was found "seriously unwell" in Wagga Wagga earlier this week.

A police spokeswoman says investigators are waiting on the results of "further testing" following the completion of a post-mortem examination.

AAP understands the autopsy failed to establish what caused the infant's death on Monday.

The two-month-old died in hospital after he was found unwell at his home in Kooringal near Wagga Wagga.

Andrew Crichton, who's believed to be the baby's father, was arrested at the scene and later released pending further inquiries.

The 32-year-old repeatedly cried out "I'm sorry" as he was taken into custody, neighbours said.

Police initially said the death was being treated with a "degree of suspicion".

AAP understands detectives have sent items from the crime scene for further testing.

Police are yet to confirm if the case will proceed with local or homicide detectives.

The baby's mother has assisted the investigation and is receiving support, police say.

The family is understood to have lived in Wagga Wagga for some time.