But privately, contrasted by those public displays of concern and devotion, Mr Newson was almost immediately messaging other women seeking sex; sending one a sexually explicit image of himself, reaching out to a woman he didn't know online to tell her she was "hot" and telling another to "let your sister know I'm single".

Crown prosecutor Lee Carr, SC, told a jury in Mr Newson's murder trial on Tuesday that in the days after Ms McBride's disappearance, while volunteers and police searched for her around Muswellbrook and handed out missing person fliers, Mr Newson was in Sydney, messaging friends about how he was driving an Audi R8.

Mr Newson, now 43, has pleaded not guilty to murdering Ms McBride at Muswellbrook on September 30, 2014, and dumping her body in bush about 25 metres from Bunnan Road at Owens Gap.

The prosecution allege Mr Newson - who Mr Carr said had competed in a number of professional Muay Thai fights - intercepted Ms McBride after she left a visit with her daughter and killed her by inflicting a number of blows to her head and back.

During his lengthy opening address, Mr Carr repeatedly touched on the juxtaposition between Mr Newson's public displays of concern and the private messages he was sending other women.

He said that contrast formed part of the prosecution's circumstantial case against Mr Newson, likening the jury's task to completing a jigsaw puzzle.

"Nowhere in those folders is what people may refer to as a smoking gun," Mr Carr said, gesturing towards a long wall of folders containing evidence in the case. "There is no statement from any person that says I saw Sayle Newson kill this lady or I saw him assault her. There is no tape recording of him admitting that and he certainly didn't admit it to police. What the Crown brings for your consideration in this trial is a circumstantial case."

Mr Newson and Ms McBride met at a drug rehabilitation centre on the Central Coast in 2013 and started a relationship in August, 2014.

Over the next two months Mr Newson repeatedly drove Ms McBride up to Muswellbrook to visit her daughter at her ex-partner's house.

About 2pm on September 30, Ms McBride left the house in Calgaroo Avenue and said she was walking to McDonald's to get picked up but was never seen again.

Her skeletal remains were found at Owens Gap, outside Scone, on August 7, 2016, almost two years after she went missing. The discovery was a significant breakthrough in the case and an event shrouded in secrecy.

Mr Carr said Ms McBride's skeletal remains were intact, except bones from her hands and forearms were missing.

He told the jury detectives delayed publicly announcing the discovery for four days and established a fake "crime scene" at another location, distributing photographs and vision of the dummy discovery site to the news media.

Mr Carr told the jury Mr Newson later called Ms McBride's father, Steve McBride, and said "he had heard that somebody was in possession of [Carly's] hand".

The only people who knew about the condition of Ms McBride's skeletal remains were the police, her parents and those at the forensic medicine department at John Hunter Hospital, Mr Carr said,

"That detail was never released to the press," he said.

Later, Mr Newson allegedly told Mr McBride he knew the exact location where his daughter's remains had been found.

"I've hunted that area I know that area like the back of my hand," Mr Newson allegedly said. "It's not something I would admit to anyone else because it sounds incriminating."

Mr Carr said Mr Newson did in fact know where the body was found, which Mr Newson said he worked out from watching footage on the news.

"The film released to the press was of the fake scene," Mr Carr said. "There wasn't any film of the skeleton or any footage to zoom into to explain the knowledge of the lack of hands. The description of the scene is accurate and the knowledge of the hands, these are all pieces of circumstantial evidence."

The trial continues.