Bulgaria announced Thursday that it has confirmed the existence of a third suspect in the 2012 bombing that killed five Israeli tourists and their tour bus driver in the city of Burgas, Reuters reported.

“Besides the two identified suspects, a third person was directly involved in the July 2012 bus bombing at Burgas Airport,” Chief Prosecutor SotirTsatsarov told the Bulgarian News Agency.

Bulgaria has already identified two alleged Hezbollah operatives as suspects in the bombing — 32-year-old Meliad Farah, also known as Hussein Hussein, an Australian citizen, and 25-year-old Hassan El Hajj Hassan, a Canadian citizen, both of Lebanese origin. Even though the two are still at large, Tsatsarov had previously said that they would be indicted by March of this year, but the identification of the new suspect is expected to delay the indictment.

Bulgaria has submitted an extradition request to Lebanon, but have not received an answer, according to the German DPA news agency.

“The identification of the new suspect will extend the investigation and there will be new requests for legal help from abroad… It means we will need just a little more time,” Tsatsarov added.

The bombing is suspected to have been in retaliation for the assassination of Hezbollah military wing chief Imad Mughniyeh in 2008, an operation which was widely believed to have been carried out by Israeli agents.

Following the attack and subsequent discovery of the connection to Hezbollah, the European Union in late July officially labeled Hezbollah’s military wing a terrorist organization. The decision to blacklist the organization was decided by a unanimous vote among the EU’s 28 foreign ministers.

The Associated Press contributed to this report.