A nine-month-old baby girl whose body washed ashore on a Gold Coast beach was "sacrificed" by her family across the border in New South Wales, police in Queensland believe.

Sources familiar with the investigation say the family of four were tracked on CCTV travelling from the Gold Coast to the Jack Evans Boat Harbour in Tweed Heads on Saturday.

It's alleged the naked baby girl was thrown into the harbour and her empty pram left alongside the waterway. Police divers are continuing to search the harbour today.

Police divers search Jack Evans Boat Harbour, where it's believed the baby entered the water. (9NEWS)

Queensland police then captured images of the now trio catching a bus at Coolangatta and returning to Queensland, sources said.

The baby's body is believed to have drifted in the current for two days before washing ashore at a Surfers Paradise beach where she was found by passers-by at around 12.30am on Monday.

Queensland Police confirmed in a statement last night that it had been established the baby's death occurred in New South Wales but gave no further details.

(9news)

The baby was found on the shoreline. (9NEWS)

Tributes at a beach lookout near where the baby girl was found dead on Monday morning. (9NEWS/Darren Curtis)

Emergency services at the scene where the baby was found in the early hours of Monday morning. (Nine)

The child's father, a 48-year-old homeless man, will face an extradition hearing in Southport Magistrates Court today. He's expected to be charged by police upon his successful return to New South Wales.

But it's believed the girl's mother, 23, will not face charges.

Police sources in Queensland allege the mother admitted to knowing about the planned "sacrifice" - as it has been described - but only the father would be accused of throwing her into the water.

Police sources have also said the mother has been released from custody and it's understood she has been placed in the mental health system in Queensland.