Friday marks two years since Saudi journalist Jamal Khashoggi was murdered inside the Saudi consulate in the Turkish city of Istanbul.

The 59-year-old Washington Post columnist was killed at the consulate on October 2, 2018, after he entered the premises to obtain paperwork for his planned marriage. His body, which Turkish officials say was dismembered by Saudi officers, has never been found.

The Saudi government called the assassination a “rogue operation” after repeatedly denied any involvement in the incident for weeks.

Activists and human rights groups have said the murder was premeditated and carried out upon the directive of Saudi Crown Prince Mohammed bin Salman (MBS), the kingdom’s de facto ruler, a charge Riyadh denies.

The CIA concluded that the crown prince ordered the killing, an accusation denied by the government in Riyadh.

Agnes Callamard, the United Nations special rapporteur on extrajudicial, summary or arbitrary executions, also found “credible evidence” that MBS and other senior Saudi officials were liable for the killing, in an investigative report published in June 2019. She has been following the case since the murder.

Callamard said it was clear from the start that it would be very hard to get justice for Khashoggi, as the Saudi justice system was prone to political manipulation.

“I think we need to ensure we do not get ourselves held hostage by the inadequacies of the Saudi justice system,” she told Al Jazeera.

“It incumbent upon other actors outside Saudi Arabia to put pressure and do all they can to make sure the accountabilities are delivered,” she added.

In September, the Saudi chief prosecutor announced the final verdicts for eight defendants tried in the Khashoggi case. Five of the defendants were sentenced to 20 years, one to 10 years and the two remaining to seven years each in prison.

Saudi authorities failed to disclose the identities of the defendants or who got which sentence, strengthening allegations that the trial was merely a coverup.

Turkey opens its own case

Meanwhile, Turkey in July opened its own trial of 20 Saudi nationals indicted over the killing of the Saudi journalist.

The suspects in the trial include two former senior aides to MBS.

According to the indictment, Saudi Arabia’s former deputy intelligence chief Ahmed al-Asiri is accused of establishing a hit team and planning the murder of the journalist, who wrote critically of the Saudi government.

The former royal court and media adviser, Saud al-Qahtani, is accused of instigating and leading the operation by giving orders to the hit team.

Other suspects are mainly the Saudi officers who allegedly took part in the assassination operation. The Turkish prosecutors have issued arrest warrants for the suspects.

“We know that it will be very difficult to get those who ordered the crime in front of a court, particularly if it is MBS as CIA suggested over a year ago,” Callamard told Al Jazeera.

“That said, there are other ways of ensuring at very least the truth is being delivered and at the very least, Saudi Arabia feel the pressure politically and diplomatically,” she said, calling on the international community for action.