The car is believed to have been the getaway vehicle in the December 2003 shooting of Kinniburgh, while Blewitt - a person of interest in that murder - likely died inside the same vehicle a year later.
Police had believed Blewitt was buried somewhere in northern Victoria but honed in on a Yarrawonga property after receiving information following last week's public appeal and announcement of a $100,000 reward over the Kinniburgh murder.
They have searched inside and around a shed on the property with the help of a forensic archaeologist and anthropologist, a cadaver dog and a small excavator.
The current and previous owners of the property have no links to the cases but police say one of their persons of interest had a link to Yarrawonga at the time Blewitt went missing in April 2004.
- AAP