By Servet Gunerigok

WASHINGTON

The U.S. on Friday expressed "sadness" over the death of Saudi journalist Jamal Khashoggi inside Riyadh's consulate in Istanbul.

Khashoggi died after a brawl inside the consulate and 18 Saudi citizens have been arrested over the murder, said the Kingdom.

White House Spokeswoman Sarah Sanders said in a statement that the U.S. acknowledged Saudi Arabia’s announcement and was "closely" following the developments.

"We will continue to closely follow the international investigations into this tragic incident and advocate for justice that is timely, transparent, and in accordance with all due process," Sanders said. "We are saddened to hear confirmation of Mr. Khashoggi’s death, and we offer our deepest condolences to his family, fiancée, and friends."

Khashoggi, a columnist for The Washington Post, had gone missing since entering the Saudi Consulate in Istanbul on Oct. 2.

On the day of his disappearance, 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.

*Sibel Ugurlu in Ankara contributed to the story