Police are closing in on Karen Ristevski's killer with new evidence giving police the confidence they'll crack the year-long mystery.

Ristevski went missing on June 29 last year from her luxury home in Avondale Heights in Melbourne's northwest.

Her husband Borce Ristevski said she left the house to clear her head about 10am after they had an argument over money.

Police have now identified a car the same make and model as Ristevski's in CCTV footage, driving towards an area near where she was found dead on February 20.

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The 47-year-old's body was discovered wedged between the trunks of two fallen trees off Loch Road at Mount Macedon in Melbourne's northwest. Police would not comment on whether they knew the cause of death, but it is being treated as a homicide.

Police have identified a black Mercedes-Benz SLK coupe, the same as Ristevski's, driving northwest along Old Calder Highway over a railway crossing in the northwest Melbourne suburb of Diggers Rest at 11.12am on the day she disappeared.

Police believe the car is similar to the one which belonged to Ristevski. There are several hundred of those cars in Victoria, but police have eliminated the majority of owners from being in that area the day Ristevski disappeared.

Borce and Karen Risteveski. Borce is a suspect in the death of his wife.
Borce and Karen Risteveski. Borce is a suspect in the death of his wife.

Inspector Tim Day said police had less than 20 car owners to speak to before they could determine the car belonged to Ristevski.

Police said they explored a possible route to Ristevski's burial area but would not give more detail. They also would not confirm if they had collected more footage.

Day said Ristevski's husband Borce, who has maintained his innocence, was still a person of interest.

"Yes he is a suspect, I won't go into if there are others," Day said.

"What makes him a suspect I'll leave others to judge why."

Ristevski said he drove his wife's car the day she disappeared to test a faulty fuel gauge.

He said the fuel gauge fixed itself when he drove over a bump near the Calder Park Raceway.

Mercedes mechanics however told Fairfax Media the expensive car was "not an FJ Holden" and it would not have been fixed by a jolt.

"I have been dealing with Mercedes for more than 35 years and I have never heard of this," Nick Theodossi, of Nick Theodossi Prestige Cars, said.

Pings from Mr and Ms Ristevski's respective mobile phones had also been detected by transmitter towers along Melbourne's Calder Highway on the day of her disappearance.

Ms Ristevski's mobile phone was reportedly tracked near Gisborne, 40km northwest of the family home.

The data also revealed that Mr Ristevski's mobile phone was switched off for about two hours that day.

Detectives last year also took CCTV footage from 60 cameras at two service stations at Calder Park and studied video from Toolern Vale General Store.

Day would not comment on Mr Ristevski's statement in relation to driving his wife's car to test the fuel gauge.

"I'm aware that's what his version of events are," he said.

Speaking to media today, Day said he was not concerned this case would go unsolved and investigators were motivated by the truth.

"I have every confidence in the missing person squad investigators and every confidence it's a matter of time," Insp Day said.

"The person who did this has a story to tell and only gets one chance."