Crucial new clues unearthed in the case of missing Melbourne mother Karen Ristevski.

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

Crucial new clues have been revealed in the case of missing Melbourne mother Karen Ristevski, nearly two months since she disappeared from her Avondale Heights home.

According to The Herald Sun, the 47-year-old’s mobile phone was detected by transmitter towers on the Calder Highway on June 29, the day she disappeared. The “pinged” location was near Gisborne, roughly 40km northwest of her Oakley Drive home.

Towers also detected the phone of her husband, Borce, on the same highway near Diggers Nest, some 20km in the same direction.

Data also reportedly shows that Mr Ristevski’s phone was switched off for two hours that day.

According to the paper, Mr Ristevski last month told police that he had previously forgotten to mention having driven his wife’s car up the Calder Highway on the day she disappeared in order to test the faulty fuel gauge.

He reportedly claimed that he had driven the Mercedes-Benz until a bump in the road appeared to correct the gauge, and then returned home.

The 52-year-old has denied having any involvement his is wife’s disappearance, and maintains that she vanished after taking a walk to “clear her head” following an argument about household finances.

Mrs Ristevski has not accessed her bank accounts or used her mobile phone since her disappearance.

Karen (centre) with her daughter, Sarah, and husband, Borce. Via Nine News.

On Thursday, Victoria Police revealed they were focusing their attention on a "rural area" northwest of Melbourne,

“Investigators are appealing for anyone that resides in this area to consider checking their properties for any changes or any suspicious activity since the disappearance of Karen,” Acting Sergeant Melissa Search told media.

Mr Ristevski has reportedly stopped cooperating with police, as has the couple's 21-year-old daughter, Sarah, in support of her father.

Authorities are treating Mrs Ristevski's disappearance as suspicious.