NGOs denounced the ruling as an attempt to silence whistleblowers, but prosecutors said the case had nothing to do with the scandal that brought down the government.
The private investigator behind the "Ibizagate" scandal in Austria has been convicted of drug offences.
Julian Hessenthaler -- whose video led to the fall of the Austrian coalition government in 2019 -- was found guilty of cocaine trafficking and receiving falsified identity documents.
He was sentenced to three-and-a-half years in prison by the regional court in Sankt-Pölten, according to AFP.
NGOs have denounced the verdict as "devastating" and claim that the conviction is an attempt to silence Hessenthaler.
The 41-year-old was at the centre of one of Austria's most dramatic political scandals.
Hessenthaler shot a hidden camera video on the island of Ibiza of Heinz-Christian Strache, the former Austrian vice-chancellor and leader of the far-right FPÖ party.
In the footage, Strache was heard promising state contracts in exchange for party donations ahead of the 2017 parliamentary elections.
The former vice-chancellor resigned after the Ibiza video was released in 2019 and was convicted of corruption last August.
Former Chancellor Sebastian Kurz and ex-Finance Minister Gernot Blümel have also left Austrian politics as the "Ibizagate" continues to rumble.
In 2020, Hessenthaler was himself detained in Germany on a European arrest warrant and his conviction has sparked a backlash from NGOs and fears for press freedoms.
Fifteen NGOs -- including Amnesty International and Reporters Without Borders -- have argued that Hessenthaler is a whistleblower who allowed the publication of information of public interest.
The NGOs have also claimed that he had been prosecuted under a false pretext to silence him.
"This trial offers a devastating vision for confidence in the independence of the judiciary and the rule of law," said Thomas Lohninger, director of the Austrian organisation epicenter.works.
"There was no evidence against the defendant during the trial other than the statements of two witnesses," Lohninger told AFP.
Prosecutors had stated that the trial had "nothing to do" with the "Ibizagate" scandal and was due to a "chance discovery" of drugs.
Hessenthaler was accused of selling over 1.25 kilograms of drugs to an acquaintance in 2017 and 2018 at a price of €40 per gram. He also allegedly presented false documents during a police check in 2019.
The private investigator's lawyers have said they would appeal the verdict.