Interviewed at Anadolu Agency's Editors' Desk in Ankara, Abdulhamit Gul said Turkish prosecutors are investigating the issue "deeply, successfully and in every step of the way."

The Istanbul prosecutors' office will reveal the truth behind the disappearance of Khashoggi, Gul said, adding that "whatever the international law requires will be done."

Khashoggi has long been feared killed after he entered the Saudi Consulate building in Istanbul on Oct. 2 and was never seen leaving.

On the same day, 15 other Saudis, including several officials, arrived in Istanbul on two planes and visited the consulate while Khashoggi was still inside, according to Turkish police sources. All of the identified individuals have since left Turkey.

On Wednesday, crime scene investigation units arrived at the Istanbul residence of Mohammad al-Otaibi around 4.40 p.m. local time (1340 GMT). Al-Otaibi left Turkey for Riyadh on Tuesday.

Officials from a joint Turkish-Saudi team completed an investigation into the case early Thursday after searching the Saudi consul general's official residence as well as the Saudi consulate building in Istanbul.

The Turkish team concluded its search for evidence in nine hours and left but returned to the Saudi consulate to continue searching the premises.