Argentina’s Senate voted on Thursday to approve a controversial agreement with Iran to probe the 1994 bombing of a Jewish center in Buenos Aires.

The agreement calls for Argentina and Iran to form a joint “truth commission” to investigate the attack on the AMIA Jewish center, which left 85 people dead and 300 injured. Afterward, Argentine and Iranian judicial officials are to question five Iranian suspects, including Defense Minister Ahmed Vahidi, in Tehran.

Jewish groups have pilloried the deal as tantamount to allowing a murderer to investigate his own crime. Earlier in the month, Jewish community head Guillermo Borger said working with Iran would allow for another attack on the country’s Jewish community.

Government officials, including President Cristina Kirchner and Foreign Minister Hector Timmerman, himself Jewish, say the deal is the only way to move forward with Iran, which has refused to turn over the suspects.

The Senate vote passed 39-31, with most of the “no” votes coming from the opposition. The deal still must be approved by the lower house, which is also controlled by government allies, according to Reuters.

Lawmaker Daniel Flimus from the ruling party defended the deal, though admitted Iran may not cooperate.

“We know this is difficult if there are hidden motives on the other side of the signing of this memorandum,” Flimus said during the Senate debate, according to a Reuters report. “If there’s a lack of collaboration on the other side of the memorandum, the Argentine case … will be strengthened because it will be even clearer who is guilty.”

On Friday, hundreds of Argentinians in Israel are expected to protest against the deal outside the country’s embassy in Herzliya.

At the demonstration, the organizers are scheduled to read a letter to the Argentinian ambassador. It reads, in part, that Argentina “cannot sign any international agreement with a dictatorial regime who represses the political opposition brutally, who oppresses its people, violating human rights especially women’s rights, and freedom of expression, freedom of belief and religion, and denies the Holocaust, as does the current Iranian government.”

Amnesty International in Argentina praised the deal, saying it offered a possible path toward justice.

“Although it does not guarantee in any way the success of the investigation, it creates an opportunity to move forward towards justice and reparations for the victims,” the group said.