Detective Homicide Squad Commander, Detective Superintendent Danny Doherty said a post mortem revealed the Queensland girl – who was reported missing from Mount Wilson on January 14 – suffered a gunshot wound.

“Charlise … suffered a fatal gunshot wound and that’s how she died,” he told reporters on Tuesday.

“It’s important that the public know that this is a unimaginable and egregious murder of a child. Investigations are still ongoing.

“The crime scene at Mount Wilson is ongoing.”

The child’s disappearance triggered an intensive five-day search of bushland until her body was discovered a week ago, in a barrel dumped near the Colo River northwest of Sydney.

Justin Laurens Stein, 31, faced court last week charged with murder after being arrested at a Surry Hills unit.

Police have interviewed Charlise’s mother Kallista who provided a statement that she was not present at the property at the time of the murder and corroborated other key evidence.

Charlise lived with her grandmother at Coolangatta and was holidaying in the Blue Mountains with her mother and her fiance, Stein.

Stein was alone with Charlise on the night of her murder, Det Supt Doherty said.

Police have released CCTV footage of a red Holden Colorado ute that was seen driving around and towing a boat in the inner Sydney suburb of Drummoyne followed by the northern areas of Wisemans Ferry and Colo River.

They allege Stein had previously tried to float a “covered up” boat at an inner-Sydney dock after buying sandbags from a hardware store, before travelling back to the Colo River.

A plastic barrel was missing from the property indicating a “high probability” of the murder taking place at the remote estate near the Blue Mountains, Det Supt Doherty said.

Police are appealing to anyone who may have seen suspicious activity in those locations.

“We’re working on behalf of Charlise. We’re trying to provide answers to her family and deliver justice on her behalf more importantly”.

-AAP