Detectives have released the last known image of missing Ballarat mum Samantha Murphy as the investigation suffered a setback.

The CCTV footage shows Murphy running at 7.16am on Sunday near her home before she disappeared.

It is one of few public leads police have as they continue the increasingly desperate search for the 51-year-old.

Residents in the area have been asked to review any CCTV they have between 7-11am in case Murphy was caught on camera.

In a discouraging setback, items found in bushland and considered of “interest” on Wednesday are not believed to be connected to the mother-of-three’s disappearance.

Police said the discoveries at Woowookarung Regional Park were not related to the search.

The last known footage of Samantha Murphy on her run. Photo: Victoria Police

Fears are growing for Murphy as neighbours aid a search effort and volunteers comb through property and paddocks.

She was last seen leaving her Eureka Street home at Ballarat East about 7am on Sunday to go for a trail run.

Crews have been searching for her in the Canadian Forest area since Monday. On Wednesday, their focus shifted to the suburb of Mount Helen, east of Geelong Road.

The search area still extended far and wide, though, with State Emergency Service volunteers canvassing paddocks in nearby Warrenheip, lifting up tarps and dodging electric fences and alpacas to pick through scrub.

The Warrenheip search crew was one of many trying to cover as much ground around Ballarat as possible while it was still light on Wednesday, after SES volunteers earlier crowded Woowookarung Regional Park.

Samantha Murphy’s disappearance has shocked the community in Ballarat.

Local Trudi Hooper visited Buninyong Police Station where officers stuck highlighted maps to a whiteboard, showing where the public can help the search effort.

The local mother joined other neighbours poking through bushland in the hopes of finding a phone, watch, earphones, or any of Murphy’s belongings.

“It’s horrible, It’s too close to home,” Hooper said.

“How can you just go for a run in the morning and not come home? It doesn’t make sense.

“I was hoping that I’d get out here and they’d tell me it has been called off and that she’d been found already.”

Search crews were expected to finish at last light on Wednesday before resuming their hunt for Murphy early on Thursday.

Police said her disappearance was out of character and they were concerned for her welfare due to the length of time she has been missing.

Murphy is Caucasian, about 173 centimetres 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.