Homicide squad detectives believe a man's body may have been by the side of a road at Carrum Downs, in Melbourne's south-east, for up to three weeks.
The body was found among trees between Worsley Road and the Eastlink Tollway on Wednesday afternoon.
Police do not know who the man is or how he ended up dead on the side of the road.
Detective Senior Constable Jennifer Booth is hoping a post mortem examination will shed some light on the case.
"A post mortem examination will be conducted we're hoping that will proffer some more answers and circumstances surrounding his death and how he came to be in this location," she said.
"Based on those finding we'll make some decisions from there as to how the investigation progresses.
"We don't know the identity of the male so I'm unable to say if it is a missing person or not."