The 37-year-old's body was found by council workers in a drain at Toolooa after businesses in the area reported a foul smell.

Acting Detective Inspector Luke Peachey said the body had been transported to Rockhampton last Friday where an autopsy was conducted.

"We can rule out he recieved any blunt force wounds or stab wounds," he said.

He said pathologists had sent off a number of samples and were awaiting toxicology reports that would hopefully provide a clearer picture as to what happened.

"Hopefully it will show further direction as to how he has died.

"We are still investigating cause of death but we are hoping to downgrade that shortly to non-suspicious."

He said a crime scene had also been established at Mr Ceremuga's home, which is about two kilometres from where his body was found.

"Police arrived (at Mr Ceremuga's home on Friday) and found an amount of what appeared to be dried blood within the residence and also on the back door of the residence," he said.

"We can't rule out foul play ... we are still keeping a very open mind ... at this stage we haven't found any evidence of a third party involvement."

Acting Inspector Peachey said the last known sighting of the Gladstone local was at Barney Point on May 11.

"From an interim report, we last saw him at Barney Point beach, at which time he was spoken to by police about his behaviour there," he said.

"It appeared at that time that he was under the influence of something and was trying to go for a swim at the beach."

Mr Ceremuga's family were distressed and "seeking answers", Acting Inspector Peachey said as he called on assistance from the public to determine the man's final moments.

"We need some assistance of final movements before he was found in the stormwater drain," he said.

The man was known to police.