Why Karen Ristevski's killer may get away with murder, a former detective explains.

On April 18 2019, Borce Ristevski was sentenced to nine years in prison for the death of Karen Ristevski.

A former lead homicide detective has expressed his concern that the investigation into the death of Melbourne mother Karen Ristevski is going cold.

Speaking to The Australian, former Victoria Police Detective Senior Sergeant said it was worrying that no arrests had been made in the six weeks since the 47-year-old’s body was discovered in bushland at Macedon Regional Park.

“Obviously they have some circumstantial evidence which arouses suspicion but they are falling short of being able to charge anyone,” Mr Bezzina said.

“You’ve got to be pretty damn sure about your facts before you start charging someone because ultimately it draws so much media attention.”

The mother-of-one's husband, Borce Ristevski, is the primary suspect in the case, according to his lawyer, but has consistently maintained his innocence.

While they are likely to be looking at Mr Ristevski closely, Mr Bezzina said the investigators will certainly be keeping an open mind and "casting a wide net".

“Maybe it was no one associated to the ­deceased," he told The Australian. "Maybe she got picked up by a total stranger.”

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Mrs Ristevski was reported to be last seen alive walking out of her home on Oakley Drive, Avondale Heights, on June 29, 2016, to “clear her head” following an argument over money with her husband.

She never returned. No money was withdrawn from her account, no calls made from her mobile phone.

An intensive missing persons investigation was launched, that saw police scaling bushland and rural properties around Toolern Vale and Gisborne, north west of Melbourne.

Then in February 2017, the discovery. A walker stumbled across human remains partially buried between two fallen trees near Mount Macedon.

DNA testing later revealed them to be those of Mrs Ristevski.

Her cause of death is yet to be announced.

If you have any information that you believe may assist police with their inquiries, please call Crime Stoppers on 1300 333 000.