Carlos Menem and Cristina Fernandez de Kirchner appeared in separate courtrooms in the capital on Thursday.

Menem, who served as president for two terms from 1989 to 1999, is among 13 defendants who have gone on trial for bribery and hindering the investigation into the deadly 1994 Jewish center bombing. The original investigation failed to convict anyone following a three-year trial that ended in 2004. But the presiding judge in that case, Juan Jose Galeano, is now among the defendants on trial.

Ruben Beraja, the former head of the DAIA Jewish political umbrella group, is also a defendant, accused of his involvement in the alleged bribery. Menem allegedly endorsed the a payment of  $400,000 to an auto mechanic who was urged to testify against police officers and thus embarrass a political rival of Menem’s. In 2005, a jury dismissed Galeano and the case was transferred to federal judge Rodolfo Canicoba Corral and prosecutor Alberto Nisman.

As a result of the Nisman-led investigation and his suspicion of Iranian involvement in the attack, Argentina is seeking the extradition of seven Iranians for their alleged roles in the bombing.

The accusation against Kirchner, who served as president for two terms from 2007 to 2015, relates to a pact that Argentina signed in 2013 with Iran to jointly investigate the bombing. The pact led to accusations by Nisman, who was the lead prosecutor on the AMIA case, that Kirchner and her administration agreed to cover up Iran’s involvement in the bombing in exchange for oil.

Nisman was found dead in his Buenos Aires apartment in January 2015 on the eve of his presenting the case against Kirchner; the cause of his shooting death remains undetermined.

A federal court in 2014 ruled the agreement was unconstitutional, prompting the government to appeal. In December 2015 the new Argentine government under President Mauricio Macri withdrew the appeal, effectively voiding the agreement.

Argentine courts have accused Iran of orchestrating the attack, though Iran has denied any involvement.

Cristina Fernandez de Kirchner on Thursday told Judge Claudio Bonadio that the agreement was made in order to make headway in the investigation and to allow that the accused Iranians to testify in Teheran before an Argentinean judge.

“The accusation of treason is ridiculous. The government is behind this accusation and the only treason here is to pressure opposition leaders, to use the justice department to prosecute politicians from the opposition,” she told journalists after the one-hour testimony at the federal courthouse in Buenos Aires.

Last week, former Foreign Minister Hector Timerman, who is accused along with Kirchner and other former government officials, refused to answer questions from the judge. Instead, he presented a 160-page statement in which he denied that he had a secret meeting in Aleppo, Syria, to negotiate the agreement with Iran. It said that the pact was meant to advance the AMIA investigation.

Both former presidents have immunity after winning seats in the Argentinean national senate — the upper chamber of the Parliament. The parliament can vote to revoke the immunity of parliamentarians after a request from the Justice Department.