ISTANBUL - A Turkish court this week added new defendants to the case against Saudi officials charged in the killing of journalist Jamal Khashoggi, state media reported, in a trial that Ankara says is needed to reveal the full truth behind the killing.

Khashoggi, a critic of Saudi Crown Prince Mohammed bin Salman, was last seen entering the Saudi Consulate in Istanbul on October 2, 2018. Turkish officials believe his body was dismembered and removed; his remains have not been found.

In September a Saudi court jailed eight people for between seven and 20 years over the killing, in a trial that critics said lacked transparency. None of the defendants was named.

At a hearing Tuesday in Istanbul, only the second session of a trial that opened four months ago, the court accepted a second indictment adding six defendants to the list of 20 Saudi officials already being tried in absentia.

The latest indictment accuses a vice consul and an attache of "premeditated murder with monstrous intent." The four others, also Saudi nationals, were charged with destroying, concealing or tampering with evidence.

The court heard testimony from Egyptian opposition activist Ayman Noor, a friend of Khashoggi, before adjourning the case to March 4 and extending a process that has kept Khashoggi's killing in the public eye and further strained relations between Turkey and Saudi Arabia.

Yasin Aktay, a member of President Recep Tayyip Erdogan's AK Party and an acquaintance of Khashoggi, said a just verdict could not have been expected from a Saudi court that was ruling on senior Saudi officials.

"The events actually transpired in Turkey. If we have a concern about justice, there is no other way than to have confidence in Turkish courts," he said after Tuesday's hearing.

The first indictment accused two top Saudi officials, former deputy head of Saudi Arabia's general intelligence Ahmed al-Asiri and former royal court adviser Saud al-Qahtani, of instigating murder.

It said 18 other defendants were flown to Turkey to kill Khashoggi, a prominent and well-connected journalist who had grown increasingly critical of the crown prince.

Noor said in court that Khashoggi called him about 10 days before he came to Turkey and broke down in tears as he asked Noor to delete an interview Khashoggi had recorded with him.

"Qahtani had called him from Saudi Arabia. He threatened him with very strong language, saying he knew his children and was close to them," Noor said, according to Turkey's state-owned Anadolu news agency.

Qahtani, a top aide to Crown Prince Mohammed who was sacked and was later sanctioned by the U.S. Treasury over his suspected role, has not faced trial in Saudi Arabia. He did not respond to requests for comment at the time of the Saudi trial.

The CIA and some Western countries believe the crown prince ordered the killing, which Saudi officials deny.

Reporters Without Borders said it was disappointed by the court's rejection of its request to join the case as a civil party and would continue to closely monitor the case and call for adherence to international standards.