Samantha Murphy: Cop makes bleak admission about the endless search for missing Ballarat mum after discovery by a dam renewed hopes of finding her body

A former cop has said the likelihood of finding Samantha Murphy's body dwindles with each passing day as the four month search continues.

The mother-of-three, 51, vanished during a morning run through Ballarat's Canadian State Forest on February 4.

Police are still no closer to finding her body, despite Patrick Orren Stephenson, 22, being charged with her alleged murder a month after she disappeared.

Hopes were raised that recovery efforts were a step closer after detectives found Ms Murphy's phone in a dam 14km from her home on May 29.

But despite a 'targeted' search operation last week, her body has still not been found.

Nigel Phair, from UNSW's Institute for Cyber Security, said that 'as every day goes on, it's less and less likely' that they will recover Ms Murphy's remains. 

'The phone was obviously the interesting one because the assumption was that the body would have been in that lake, near where they found it. I'm guessing the divers have gone through that multiple times and haven't found anything,' Mr Phair told Yahoo News.

A former federal police officer, Mr Phair said that the problem facing Victorian Police detectives is that they will one day have to divert their resources to other priorities. 

'I think they can keep searching for a lot longer, it's the resourcing they put into that, to prioritise this over rather, what are going to become more urgent matters, that's going to be the issue,' he added.

'There will always be a detective assigned to the case. But whether it's the sole case or becomes one of their many cases, that's what's going to happen over time as the next priority overtakes.'

A renewed search took place over two days last week as officers scoured across a 'targeted' area of the forest.   

'Detectives from the Missing Persons Squad as well as a range of specialist resources from across Victoria Police were involved in the search,' a police statement read.

'Since February, police have regularly undertaken a range of inquiries and small-scale searches as part of the current investigation.

'Samantha's family has also been advised of the search.'

Mr Phair said despite Ms Murphy's phone being found, detectives are no closer today to finding her than they were four months ago.

Speaking from his experience in the force Mr Phair believes that detectives would be considering all possibilities, including if there might have been more than one person involved with the disappearance. 

At least one detective will remain assigned to the case so long as Ms Murphy remains missing, he added.

Mr Phair believes that police officers are likely focusing on building their case against Stephenson, who has been behind bars since his arrest. 

He said that detectives would have already handed in their brief of evidence against him and would now be working on corroborating that evidence.

Ms Murphy's phone and other items found in the search will be used in their case when it reaches the courts.

Mr Phair added that although there seems to be a lot of unanswered questions in the case detectives might be saving some crucial details for their case.

 A number of items located during the May 29 search in Buninyong are still being forensically assessed, including Ms Murphy's phone.