Det Supt Hutchinson said police believed Mr Neuendorf was murdered in the park.
Police would like to speak with anyone who saw anything suspicious in the Logan Reserve area on Thursday evening or who may have knowledge about the movements of Mr Neuendorf, who was last seen alive in Mitchelton earlier that day.
"Why was he in the Logan area that night; he's from Mitchelton?" Det Supt Hutchison said.
Officers are also appealing for public information regarding the movements of Mr Neuendorf's black 2007 Ford Falcon GT sedan, which was found in the park.
Detectives and forensic officers, as well as police divers and members of the State Emergency Service, returned to the boat ramp area on Saturday to search for clues.
-AAP