Remains found at Mount Macedon regional park near Karen Ristevski search site

Police are working to determine whether decomposed human remains found at Macedon Regional Park are that of missing mum Karen Ristevski.

9NEWS understands a witness told investigators he saw a man with a shovel at an unknown time before the remains were discovered.

The witness allegedly asked the man “what did you do to the body” but received no answer.

The remains were found by a bushwalker at 12.30pm yesterday, some 25km north from where police in December searched for missing Avondale Heights woman, Karen Ristevski, who has been missing for eight months.

While the remains are yet to be identified, Ms Ristevski’s nephew told The Herald Sun he was “shocked” at the grisly find, but did not hear anything from police.

“Obviously you fear the worst but we will just have to wait and see if it’s her. It will be a bit surprising because police told us they were searching in the Diggers Rest area,” Chris Ristevski said.

Ms Ristevski’s husband Borce told police the pair had had an argument over financial troubles on June 29, and Karen had left to “clear her head”.

A Victoria Police spokesman said the situation “hadn’t changed” and forensic testing would be undertaken to determine the identity and cause of death.

Police have not yet confirmed the gender of the remains.

A nearby resident told 9NEWS he "could not believe" remains had been found in the bushland, which is near a quiet cul-de-sac in Mount Macedon.

"We might get a few walkers, but not many people use this road at all," Ian Flannery said.

"I’m a bit flummoxed. It’s very, very unusual."

Forensic police and homicide investigators spent several hours at the site with shovels and other implements before removing the body last night for examination.

Crime scene tape has now been removed from the area.