The members of the United Nations commission investigating the killing of Saudi journalist Jamal Khashoggi consider Saudi Arabia's Crown Prince Mohammed bin Salman as the "chief responsible" of the murder, a top aide of Turkey's president said Feb. 1.

"The UN comission sees the crown prince as the chief responsible of the Khashoggi murder. They will listen the audio recordings of the murder," said Yasin Aktay, President Recep Tayyip Erdoğan's chief advisor at Turkey's ruling party.

Agnes Callamard, the UN special rapporteur on extrajudicial, summary or arbitrary executions, held one-and-a-half-hour meeting with Aktay over the killing of Khashoggi last fall in the Saudi Consulate in Istanbul.

Callamard and the accompanying delegation finalized their meetings in Istanbul on Jan. 31 and traveled to Ankara to meet with government officials and intelligence representatives.

The UN official will stay in Turkey until Feb. 2.

The UN Human Rights Office of the High Commissioner last week said that the international investigation would be led under Callamard's authorization and it would "review and evaluate, from a human rights perspective, the circumstances surrounding the killing of Khashoggi."

Callamard is being accompanied by Baroness Helena Kennedy, QC, and Professor Duarte Nuno Vieira from the University of Coimbra, Portugal.

The UN delegation Jan. 30 carried out examinations around the Saudi Consulate General in Istanbul, then spoke to İrfan Fidan, the chief public prosecutor of the city.

Callamard is going to provide her findings and recommendation on the murder investigation as a report in the UN Human Rights Council session scheduled for June.

Khashoggi, a contributor to The Washington Post, was killed at the Saudi Consulate in Istanbul on Oct. 2.

After producing various contradictory explanations, Riyadh acknowledged he was killed inside the consulate building, blaming the act on a botched rendition operation.

Turkey has sought the extradition of the Saudi citizens involved in the killing as well as a fuller accounting of the killing from Riyadh.