Tyrone Stewart, 24, said his mum had been staying at his grandmother's home in Tottenham (roughly 80 kilometres west of Narromine), having recently moved there from Canowindra.

"When I saw the report that they went to see the sunrise ... my mum doesn't go to watch the sunrise, she doesn't go bushwalking, especially in sandals," he told the Central Western Daily.

"That's a small mountain, so surely by now they'd be able to find her."

The Federal Falls walking track is roughly 2.9km long, with the initial search area ranging from the carpark to the waterfalls themselves.

"My family is in shock and they don't know what's going on ... she has a heart of gold and by now she would have contacted us," Mr Stewart said.

"It's my mother at the end of the day, I love her."

Police urged residents around Orange to be on the lookout for Ms Wallace in the event she left the area and made her way into the city.

With more than 100 hours now having passed since Ms Wallace's disappearance, her son is at the point where he is "thinking the worst".

"Usually by now, she would contact," he said.

"If she was alive, her mates would be showing her these articles, it's all over Facebook, it was on the news and she would contact to say she was safe.

"I don't reckon she's at Mount Canobolas at all. She don't go bushwalking at all. She'll go camping and fishing, but she ain't out there bushwalking watching the sunrise, that's not my mum."

Asked what would be the one thing he could say to his mum if he could, Mr Stewart added "I love ya and we want you home safe".

A search began for Ms Wallace about 8am on Wednesday, November 30, when emergency services responded to reports a woman had become separated from a companion while bushwalking at Federal Falls through the Mount Canobolas State Recreation Area, approximately 20km south-west of Orange.

Ms Wallace is of Caucasian appearance, has blonde hair and was wearing an orange jacket, black pants and sandals.

When contacted for comment on the disappearance, NSW Police were asked if any investigations had been opened in relation to criminal activity, or if they were treating the case as such.

A spokesman for NSW Police said: "The search for Esther recommenced at 8am (Monday) and police are encouraging anyone with information on her whereabouts to contact Crime Stoppers on 1800 333 000."

An item of clothing has been recovered in the search for a missing woman near Orange, the Central Western Daily understands.

The orange jacket was reportedly found by SES and ambulance volunteers in recent days, elongating the search. Media reports of a second item could not be verified.

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