A friend of Murphy said the 51-year-old was an extremely dedicated mum and described the situation as an “absolute nightmare rollercoaster”.
“I’m beside myself and I could not even imagine how (the family) are at the moment or how they’re even coping,” Virginia O’Loughlan told Sunrise.
She said Murphy had recently got back into running and was training for a race.
“Sam is extremely fit. Sam is the most strong woman I know and I’m not just talking about mind, I’m also talking about body,” O’Loughlan said.
“Sam is a fierce woman who will be doing whatever she can at the moment to make sure that she’s reunited with her family.”
Murphy’s friend praised the community for their efforts in searching for the missing mum, saying she was a sensible person who would have stuck to the tracks.
“We need as many people as we can out there, whether it be on car, on foot, horseback, motorbike, just continually looking and just trying to work out where Sam would be,” she said.
Police on Wednesday released more CCTV footage they said showed Murphy running at 7.16am on Sunday near her home heading towards Yankee Flat Rd.
Residents in the area have been asked to review any CCTV they have between 7am to 11am on Sunday.
Crews found some items on Wednesday but they were not believed to be related to Murphy’s whereabouts.
Murphy is 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 or brown singlet.