The death of the Jewish Argentine special prosecutor investigating a community centre bombing in 1994 was definitely homicide and not suicide, a federal court in Buenos Aires has confirmed.

The court said Alberto Nisman was murdered in 2015, just hours before he was due to present evidence to the Argentine Congress supporting his view that there had been an official cover-up following the terror attack on the Amia Jewish centre on July 18, 1994.

In a ruling, it said Mr Nisman’s death was the “direct consequence” of his accusations that Argentina’s then-President Cristina Fernández de Kirchner had covered up Iran’s role in the car bombing, which left 85 dead and more than 300 wounded.

In 2004, soon after Mr Nisman’s appointment as special prosecutor in charge of the investigation, he and his daughters began receiving multiple death threats. Two years later he accused the Iranian government of having planned the bomb and Hezbollah of having carried it out.

Mr Nisman was found dead in the bathroom of his Buenos Aires apartment on January 18, 2015. The death was initially classified as suicide, a verdict his family and friends dismissed as absurd.

Last December, federal judge Julián Ercolini officially ruled that Mr Nisman had been drugged, beaten and murdered, possibly by more than one person. Mr Ercolini also charged Diego Lagomarsino, an IT employee in Nisman’s office, as an accessory to murder.

Mr Lagomarsino was the last person in the apartment and the bullet that killed the prosecutor had been fired by Mr Lagomarsino’s gun, Mr Ercolini said.

That ruling was endorsed last week by Ricardo Sáenz, district attorney for the Buenos Aires Criminal Appeals Cour. The court called on the judge overseeing the case to investigate “with the speed and seriousness that such a grave matter imposes.”

Mr Lagomarsino protested his innocence this week, claiming that the prosecutor had shot himself after being “induced to do so”.

He has so far been charged only with lending the pistol to Mr Nisman.