The Saudi trial into the killing of critic Jamal Khashoggi has lacked transparency and fallen short on assigning accountability for the crime, the U.N. human rights office said Tuesday.

A Saudi court on Monday overturned five death sentences over journalist Jamal Khashoggi's murder in a final ruling that was criticized by a Turkish official as falling short of the expectations of Turkey and the international community.

U.N. spokesperson Rupert Colville, noting that the United Nations opposes the death penalty, told a Geneva briefing: "This is a case where there has not been proper transparency in the justice process, those responsible should be prosecuted and given sentences commensurate with the crime." "There is a whole issue of transparency and accountability in the case," he said.

Eight unnamed defendants were handed jail terms of between seven and 20 years in a verdict that comes after Khashoggi's sons "pardoned" the killers in May, paving the way for less severe punishment.

The court ruling underscores Saudi efforts to draw a line under the October 2018 murder as the kingdom seeks to reboot its international image ahead of November's Group of 20 (G-20) summit in Riyadh. None of the defendants were named in what was described as the final court ruling on the murder, which triggered an international outcry and tarnished the global reputation of Crown Prince Mohammed bin Salman (MBS).

"The final verdict that a Saudi court issued today regarding journalist Jamal Khashoggi’s execution inside the Kingdom’s consulate in Istanbul, Turkey fell short of meeting the expectations of Turkey and the international community," Turkish Presidential Communications Director Fahrettin Altun said on Twitter on Monday evening.

Khashoggi – a royal family insider turned critic – was killed and dismembered at the kingdom's consulate in Istanbul in October 2018. The 59-year-old critic of the crown prince was strangled and his body cut into pieces by a 15-man Saudi squad, according to Turkish officials. His remains have not been found.

Agnes Callamard, the U.N. special rapporteur on extrajudicial, summary or arbitrary executions, slammed the ruling as "one more act today in this parody of justice." "These verdicts carry no legal or moral legitimacy," Callamard wrote on Twitter. "They came at the end of a process which was neither fair, nor just, or transparent." Callamard also criticized the fact that "high-level officials" behind the murder have "walked free from the start" and that MBS has remained protected against "any kind of meaningful scrutiny."

Ines Osman, director of the Geneva-based MENA Rights Group, told Agence France-Presse (AFP) on Monday: "Since the beginning, there was never any intent to hold those responsible to account, only repeated attempts to cover it up. This verdict is the last nail in the coffin, saying 'the case is now closed.'"

Media watchdog Reporters Without Borders also condemned the verdict, with its secretary-general Christophe Deloire telling AFP the opaque trial "did not respect the elementary principles of justice."