Police have confirmed they are in the midst of a murder investigation, after a man's body was found inside an industrial woodchipper near Gympie last year.

Detectives received a tip-off in the days after the horrific incident, suggesting the death was not accidental as first thought.

The victim: Bruce Saunders.

Detective Inspector Gary Pettiford said that evidence gathered in the days after the body was found and last weekend supported the tip-off and led to police officially declaring the death as suspicious on Friday.

Nambour man Bruce Saunders, 54, died in November after falling into the woodchipper while clearing a driveway at Goomboorian near Gympie, about 150 kilometres north of Brisbane.