Radojko Djordjevic was shot multiple times in the neck and chest before his decomposing body was found in January 1985 in bushland at Marulan in the Southern Highlands.
A $500,000 reward is being offered for information that helps to solve the murder.
Radojko Djordjevic was reported missing by his wife. (HANDOUT/NSW POLICE)
Mr Djordjevic 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. His body was found five days later.
A coroner concluded he likely died between 9.30pm on January 24 and 11am on January 31.
A 49-year-old man was charged with his murder in 2003, but he was later acquitted. He has since died.
Homicide Squad Commander Virginia Gorman on Tuesday said the murder might have been politically motivated.
Conflicts within the Serbian community were 'not uncommon' at the time of Mr Djordjevic's death. (HANDOUT/NSW POLICE)
Mr Djordjevic was a prominent member of western Sydney's Serbian community and was president of the Free Serbian Orthodox Church and president of the Old Toongabbie branch of the Liberal Party.
Born in 1937 and a child during World War II, he later emigrated to Australia.
At the time of his murder, Yugoslavia - incorporating present-day Croatia, Serbia and other Balkan states - was in the process of fragmentation and conflicts within the Australian Serbian community were not uncommon.Â
"There were political power struggles within Serbian organisations in NSW," Detective Superintendent Gorman said.
"Mr Djordjevic was a prominent member of that community and there was a degree of conflict within those organisations."
Police believe he might have been picked up in a car and taken to Canberra with a number of other men before his death.
The car trip and those in the car at the time were "particularly significant" to the investigation, Det Supt Gorman said.