The decomposing body of Radojko Djordjevic was found on January 31, 1985, in bushland off South Marulan Road at Marulan in the Southern Highlands.
Radojko Djordjevic was reported missing by his wife. (HANDOUT/NSW POLICE)
He had been shot three times in the neck and chest, a post mortem found.
Mr Djordevic was reported missing by his wife when he failed to meet her and his children in Canberra for the Bojic church festival on January 26, 1985.
A coroner concluded he likely died between 9.30pm on Thursday January 24 and 11am on Thursday January 31.
Mr Djordevic was a well-known member of Western Sydney's Serbian community, president of the Free Serbian Orthodox church and president of the Old Toongabbie branch of the Liberal Party.
NSW Police believe the murder may have been politically motivated.
In 2003, a man was charged with his murder but later acquitted.
On Tuesday, police announced a $500,000 reward for information that leads to the arrest and conviction of the person or persons responsible for Mr Djordevic's murder.
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