Samantha Murphy missing: Husband pictured smiling outside police station

The husband of missing mother-of-three Samantha Murphy was spotted talking to police officers on Friday morning.

Ms Murphy, 51, left her home on Eureka Street in East Ballarat, northwest of Melbourne, to go for a run at Woowookarung Regional Park just after 7am on Sunday.

No trace of her has been found since, and it is understood homicide detectives have been called in to assist in the search as it enters its sixth day.

Mr Murphy smiled after meeting with detectives at Buninyong police station on Friday.

He spent just an hour at the station before leaving with an officer, who escorted him to his car.

Mr. Murphy appeared nonchalant as a waiting media pack bombarded him with photos.

The station is being used by emergency services as a base camp for the ongoing search for Ms Murphy.

Victoria Police Inspector Bob Heaney said detectives were relying on information from the public to help determine Ms Murphy's whereabouts.

“You know, one of the challenges we face is the area where she normally walks, it's a fairly remote area,” he told Sunrise on Friday morning.

“It's in a forest and a lot of bushland, and there's no camera coverage. That's one of the challenges we've had.”

Despair grows as the search enters its sixth day

One line of inquiry was officially ruled out on Thursday after police confirmed a woman in the CCTV footage was not Ms Murphy, as previously reported.

Victoria Police released CCTV footage on Wednesday showing a person driving north-east towards Yankee Flat Road, near the intersection with Warrenheip Road.

The woman is believed to have been Mrs Murphy, who was heading out for a 20km run through the national forest.

However, another runner came forward to reveal that she was the person pictured.

Inspector Heaney said the discovery had 'eliminated' a possible route taken by Mrs Murphy after leaving home.

He added that police still consider her disappearance not suspicious, despite missing persons unit detectives reportedly joining the search on Friday.

“Other than covering a lot of ground, a large area that we physically searched looking for Samantha, we don't know much more,” he said.

“There's been a lot of information coming in (from the public) that we need to filter so we can assess it and focus on where to look next.”

Inspector Heaney confirmed Ms Murphy was wearing an Apple Watch and had her phone with her at the time she disappeared, but said police in the area's ability to track her devices was 'limited'.

Her mobile phone had pinged in the nearby suburb of Buninyong and investigations are underway to see if the phone is still on.

In a new setback on Wednesday, officers were warned about 'items' possibly related to Mrs. Murphy's disappearance, but it was later determined that they did not belong to the missing mother.

Locals in the area have also raised concerns that the mother may have fallen into an abandoned mine shaft, which can be difficult to see on the forest floor.

Distraught daughter calls for help to bring her mother home

Earlier on Thursday, Murphy's eldest daughter Jessica and husband Michael made a desperate plea for their loved one to return home.

Through tears, Jessica urged the crowd to continue searching for her mother.

“Mom, we love you so much and we miss you and we need you home with us, please come home soon, I can't wait to see you,” Jessica told reporters.

“Mom is a very strong woman, and she is far too determined to give up this fight.”

Jessica's father thanked the community for their support in recent days as he called for answers.

“People don't just disappear into thin air,” Murphy said.

'Someone needs to know something… whether it's something small that you think is relevant, just call the police and let them know.

“It will give us a little peace of mind if we get some hope.”