"The cause of death is probably, according to initial findings, attributable to suicide by firearm, but this cause will have to be established during a future forensic examination," the office said in a statement.
Police had launched a massive manhunt for Jurgen Conings, 46, after he left his home near the Dutch border on May 17 with weapons including anti-tank rockets. Conings had threatened virologist Marc Van Ranst for supporting COVID-19 vaccines. Van Ranst and his family were subsequently moved to safety.
The body of Conings was found in the woods in Dilserbos, in eastern Belgium, by the mayor of another town who noticed the smell during a bicycle ride and alerted the police.
Belgian authorities said Conings was on a list of potential terrorists compiled by OCAM, an organisation responsible for assessing the threat of terrorism in Belgium, because of far-right tendencies.