Chris Baghsarian, 85, was taken from his northwest Sydney property early on February 13 when three men stormed the home and bundled him into an SUV.
Police repeatedly told the kidnappers they had taken the wrong person and publicly urged them to release the elderly man, who relied on daily medication.
On Tuesday morning, detectives found the remains near a golf club in Pitt Town, a semi-rural area on Sydney's northern outskirts, after members of the public reported seeing a vehicle linked to the investigation in the area a day after Mr Baghsarian disappeared.
Forensic evidence was left in a burned-out car that had been linked to the elderly man and a relevant property in Dural, investigators said.
"I have spoken to the family of Mr Baghsarian and, as you can understand, they are deeply upset," lead police investigator Andrew Marks said.
"We're all outraged this would happen to an innocent man and we will continue to investigate to identify those responsible."
Detectives are yet to formally identify the body but suspect it is the octogenarian because of the forensic links to the Dural site, which police previously searched.
"I won't go into the state of them (except) to say we can positively identify them as human remains," Detective Acting Superintendent Marks said.
Aerial footage from the Pitt Town location showed a crime scene set up among overgrown grass and dirt roads.
The historic township is about 30 minutes by road from Dural, where investigators on Friday located the kidnappers' makeshift stronghold in a vacant, derelict house back from street view.
Police believe the intended target for the abduction was a relative of underworld-linked Sydney businessman Dimitri Stepanyan, who lived on the same street as the elderly man in North Ryde.
Detectives on Sunday appealed for information about two suspicious vehicle fires linked to the case late on February 16 in Westmead, 15km from the kidnap scene.
No arrests have been made over the kidnapping of the widower, who had lived alone for about four years.
Det Supt Marks said persistent policing had produced the information required to make the find.
"We had some information from a canvass we conducted from some members of the public about suspicious activity and as soon as we had that information we conducted a search," he said.
"It's vast bushland out there and we wanted to act on that investigation immediately."
Mr Baghsarian's family spoke publicly for the first time earlier in February, describing the kidnapping as a nightmare.
"Our family is living through a nightmare we never thought possible," they said in a brief statement.
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