The judicial investigator in the Beirut Port explosion case, Judge Tarek Bitar, traveled to Bulgaria on Wednesday to interrogate the owner of the ship Rhosus, which transported the ammonium nitrate that caused the catastrophic blast in Lebanon, a judicial source told Agence France-Presse (AFP).

The move comes after a Bulgarian court refused Lebanon’s request to extradite the Russian-Cypriot shipowner, Igor Grechushkin, 48, for questioning.

The explosion on August 4, 2020, killed more than 220 people and injured thousands.

According to the source, “Bitar flew to Sofia via Istanbul and will interrogate the shipowner on Thursday.” He traveled alone, with the Lebanese embassy in Sofia arranging for a clerk to document the session, a translator, and the presence of Bulgarian judges.

Lebanese authorities hope Grechushkin’s testimony will provide key information about the ammonium nitrate shipment, including who ordered and financed it. It will also clarify whether Beirut was the shipment’s intended destination, as the ship had been docked at the port for years.

Since the disaster, investigations have pointed to the unsafe storage of large quantities of ammonium nitrate in Beirut Port. Authorities found that officials at multiple levels were aware of the risks but failed to take action.

Grechushkin was arrested at Sofia Airport in September under an Interpol red notice.

Lebanese prosecutors had charged him with “importing explosives into Lebanon, an act of terrorism that led to the killing of a large number of people.” Last week, a Bulgarian court denied Lebanon’s extradition request and ordered his release.