A car containing a dead man had been moved a number of times around Geelong before police found the corpse.
Detectives on Monday confirmed the 41-year-old man's death is being treated as suspicious.
He was found inside a Holden Commodore at suburban North Shore on Sunday by officers investigating reports of a burglary.
"Detectives believe the blue VT Holden Commodore containing the body had been moved during the past week and was not consistently in the same location," a Victoria Police spokeswoman said.
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Police want to hear from anyone who had seen the Commodore in the area before Sunday.
Anyone with information is encouraged to call Crime Stoppers on 1800 333 000 or use the Crime Stoppers online reporting page.