A tracking device was fitted by police to a vehicle used by Borce Ristevski in the months after his wife disappeared.
But the device was either removed, or fell off the vehicle, sources familiar with the investigation into Karen Ristevski's disappearance have told Fairfax Media.
Tracking devices were routinely fitted to suspects' vehicles when police suspected foul play, the sources said.
Police detectives also suspect Mr Ristevski, 52, had been advised against speaking on phones and provided with information about investigative techniques used by homicide detectives.
On Wednesday morning, Mr Ristevski managed to evade media camped outside his Avondale Heights home and visit leading criminal lawyer Rob Stary at his Queen Street offices.
Following the 9am meeting, Mr Stary confirmed his client was the "number one suspect" for his wife's murder.
Mr Stary said he had been advising Mr Ristevski since soon after Karen's disappearance.
"We've been advising him since day one really," he said.
"Obviously his wife has been found and there's an autopsy report been completed, he wants to see what that could mean.
"It's pretty clear police have him as their number one suspect."
Mr Stary declined to comment further on the case, which has intrigued Melbourne with its bizarre developments.
Ms Ristevski's body was found on Monday between two logs in bushland at the base of Mount Macedon. The 47-year-old mother and fashion boutique owner had not been seen since June 29 last year.
Her husband is believed to have told police she left their Oakley Drive home in Avondale Heighs about 10am to "clear her head" after they argued over a "sum of hundreds of dollars".
Data from Ms Ristevski's mobile phone was traced to a tower on the Calder Highway near Gisborne, not far from Mount Macedon and 40 kilometres north-west of her family home, just hours after she vanished.
On the same night, Mr Ristevski's phone was detected by another tower on Calder Highway near Diggers Rest.
Mr Ristevski was questioned by homicide detectives on July 8 and denied any involvement in his wife's baffling disappearance. He was released without charge.
He reportedly told police he'd taken his wife's 2004 Mercedes-Benz coupe for a drive on the day she disappeared to test a faulty fuel gauge.
He said the fault rectified itself after he drove the car over a bump in the road near Calder Park Raceway so he returned home, according to reports.
However, Mercedes mechanics have told The Age a faulty gauge in the luxury vehicle would not be fixed by a jolt.
One mechanic said the 2004 Mercedes has two sensors in the fuel tank and both would have to be faulty to give an empty or half-full reading.
"If it was the gauge itself then all gauges would be faulty, as they run off the same circuit board," he said.
"It's not an FJ Holden that you can fix by going over bumps. If it was broken then it is broken. Maybe a car 40 years ago, but not now."
Last July, Mr Ristevski was asked by a Channel 7 reporter in a press conference if he had killed his wife.
The press conference was abruptly ended and Mr Ristevski left without answering the question.