Victoria Police are now treating the disappearance of Ballarat mum Samantha Murphy as suspicious after she vanished 10 days ago.

The 51-year-old mother-of-three disappeared after going for a run in the Canadian State Forest in Victoria, Australia, on Sunday, February 4, with police describing her disappearance as “out of character”.

Now, after a week-long search in bushland, false CCTV hopes and empty leads, Victoria Police Chief Commissioner Shane Patton announced the case was now “suspicious”.

“It’s certainly unusual when we haven’t been able to locate any trace of her or any other evidence within that period of time,” he said during a press conference this afternoon.

"It’s suspicious, whether that means there’s foul play involved, or not, I don’t know, but obviously detectives are investigating a matter where a woman’s been missing for a significant period of time.”

Police hadn’t commented on the case since Saturday, where it was revealed they would be scaling back the search until more information came to light.

Crews scoured dense bushland in the Canadian State Forest for missing woman Samantha Murphy.

Speaking to 7 News, Former Victoria Police homicide detective Charlie Bezzina said earlier this week the decision to scale back the search meant police likely had a particular line of inquiry or theory they were looking in to.

“They’re not gonna air that, they’ll keep it close to their chest and continue to say that it’s nothing sinister or criminal at this stage, but I think everything’s on the table,” he said at the time.

Forensic expert’s theory about missing mum Samantha Murphy

A forensic expert who has analysed some of Australia’s most infamous criminals has opened up about the case, revealing his theory as to what might have happened to Murphy while she was out on her run.

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Forensic psychologist Tim Watson-Munro told Sky News that despite his expertise in criminal forensics, he has “never encountered” a case like Murphy’s.

Samantha Murphy is 51 years old and described as tall with blonde hair, last seen wearing a brown singlet.

What has baffled Watson-Munro about the Murphy case is that there has been “no evidence” to examine, explaining there is usually a small clue left behind for investigators to work with.

“I’ve never encountered a case like this where someone ostensibly goes for a run and they’re never seen again. It’s very unusual... There’s no clues at all,” he told Sky News.

He highlighted that there were a “number of possibilities” of what happened to Murphy, but that having a happy family life before disappearing only adds more questions.

This has led Watson-Munro to look at one concerning theory on what happened to Murphy.

“One of them is that she had been stalked for a while. I’ve done a lot of profiling. Stalkers love routine of their potential victims,” he said.

He theorised that a stalker may have abducted Murphy, suggesting the perpetrator could know about “evidence and covering their tracks”.

He went on to suggest she may have been abducted in a van or car and taken away from the potential crime scene that police have been combing.

Since police have now wound back their search in Canadian State Forest, Watson-Munro said it could be a clue to what authorities are thinking might have happened to Murphy.

“I gather that there was a ping from a mobile phone some distance away and then a dropout. So obviously a phone was either thrown away as a decoy or she made it that far and then the phone died out.”