Investigations continue into the death in what's believed to have been a decades-long dispute between neighbours.
A post-mortem examination is expected to be carried out today to determine what killed the 83-year-old man in front of a Joffre Court, Reservoir, home.
Family members of the dead man, who's been named by media as Michael Di Berardino, say the Reservoir neighbours had been feuding for nearly 50 years.
The great-grandfather was found dead on Joffre Street about 1pm on Monday.
"My father-in-law unfortunately was the victim, very sad when you've been telling the police for years to take this situation seriously," Maria Di Bernadino, the wife of the victim's son Paul, posted on Facebook.
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"I used to always say they'd kill each other one day."
The Nine Network reports there had been numerous restraining orders in place during the pair's 47-year-long dispute.
"Devastated, absolutely devastated, the whole family is devastated over this - it shouldn't have gone this far," son Angelo Di Berardino told reporters outside the home.
"We all loved him and he needed to be treated with justice ... not with revenge," daughter Antoniette Di Berardino said at the scene.
Another neighbour told News Corp Australia the two elderly men had argued over plants including roses.
Police say the 90-year-old man was interviewed and has since been released.
"The exact circumstances surrounding the man's death are yet to be established and investigators will await the results of a post-mortem," a spokesman said in a statement.
