A highly esteemed crime expert has spoken out saying police likely suspect a person involved in the search for missing Ballarat mum Samantha Murphy could be her killer.

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

A targeted search began in and around Mount Clear, only 5km away from where she was last seen, based on an area highlighted by intelligence derived from phone data.

Mount Clear is adjacent to the Canadian State Forest, an area Murphy was known to frequent on her runs.

Now, veteran crime expert John Silvester has aired a grim new theory as the search continues.

Speaking on Australian radio station 3AW, he said she’s unlikely to have disappeared, pointing at foul play.

A large-scale search for Victorian mother of three Samantha Murphy has failed to locate her after she went missing four days ago.

“We know it’s not self-harm or a medical issue. Why? Because the area has been searched, and they’re very confident if someone has fallen down one way or another, they would have been found.

“So that leaves you with the suggestion of foul play and probably murder.”

Locals have launched search parties in a bid to assist police in helping locate Murphy.

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However, Silvester suggested someone among the search party could be operating with ill-intent to throwing police off the scent that someone who knows Murphy or is an upstanding member of the community could be behind her disappearance.

“Police will also be considering that one of those searchers is the (alleged) killer in that they have inculcated themselves into that situation to be seen as part of the community, but also keeping an eye on what’s going on,” he explained.

He explained that police have likely ruled out that Murphy had any major secrets that the family didn’t know about.

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

New leads into Samantha Murphy disappearance

Last week Victoria Police issued a major update in the search for the missing Ballarat mother when they revealed they’re chasing a new lead thanks to mobile data information from her phone, and suspect more than one person may be involved in her disappearance.

“We are keeping an open mind, but believe the most likely scenario is that her disappearance involves one or more parties,” Detective Acting Superintendent Mark Hatt said.

“Given the extensive and detailed search that has already been undertaken, and the fact no sign of Samantha or her personal belongings has been located, we have ruled out any type of medical incident.

“There is also nothing to indicate that Samantha left the area of her own accord.”

Early in the investigation, police confirmed Murphy’s phone had also pinged 11km away from her home.

Michael (Mick) Murphy, the husband of missing woman Samantha Murphy, has appealed for any information from members of the public about the whereabouts of his wife.

Investigators are reviewing about 12,000 hours of CCTV footage and following up more than 500 pieces of information.

The Missing Persons Squad, who are in charge of the investigation, as well as detectives, specialist and local police are part of the search.

Police are continuing to ask everyone in the Ballarat East and Mount Helen areas, particularly around the Canadian Forest, to check their CCTV for possible sightings over the past four weeks.

“Finally, it’s important that people continue to avoid unnecessary and unhelpful speculation because we don’t want that to detract from the genuine investigation or potentially prevent anyone coming forward with information because they have a misconception about what has happened to Samantha,” Superintendent Hatt said.

“Police remain open to any and all possibilities, so if you know something or have seen something, then we want to hear from you.”