'We will search until we find her': police remain open-minded

Detective acting superintendent Mark Hatt said this unit had additional resources and specialist skills to deal with cases like this, particularly missing people in rural areas.

Ms Murphy was last seen on Sunday February 4 at 7am. Police confirmed her home CCTV has captured her leaving the property for a regular morning run but she has not been seen since.

Detective acting superintendent Hatt said they had not identified any "suspicious or sinister circumstances".

"I also think it's important that people avoid unnecessary and unhelpful speculation.

"We do hold significant concerns for Samantha's welfare and that is growing as the day's progress."

He said the homicide squad was not involved with the investigation.

After Ms Murphy left the view of the CCTV footage at home, police do not know where she went next.

This is why they are urging people to review their CCTV or dashcam footage from 7am on February 4.

Ms Murphy had her phone and smartwatch with her when she went out for her run.

Detective acting superintendent Hatt said these are both part of the investigation.

He said they are working with "telecommunication technicians" to get more information from the devices.

The missing persons squad will also be looking at Ms Murphy's life prior to her disappearance.

"That will be a huge part of our investigation," Detective acting superintendent Hatt said.

"Digging into the background and working out Samantha's movements in the days leading up to her disappearance and also the people that know her."

On Friday afternoon, SES volunteers focused their search to the Buninyong area where they were looking on private property.

Inspector Bob Heaney said they had expanded the search after covering a lot of ground over the last few days.

He thanked the community and volunteers from the SES and CFA who have been working across the six days of searching.

"We will continue searching until we find her," he said.

In a press release, Samantha is described as Caucasian, about 173cm tall with a slim build and shoulder-length blonde hair.

She was last seen wearing black half-length leggings and a maroon/brown coloured singlet.

Anyone who sights Samantha is urged to contact triple zero (000) immediately.

Anyone with any other information about Samantha's current whereabouts is urged to contact Crime Stoppers on 1800 333 000 or make a report online at www.crimestoppers.com.au.