King Salman of Saudi Arabia will on Tuesday embark on his first domestic tour since ascending to the throne, as Riyadh moved to contain the fallout from the killing of journalist Jamal Khashoggi. The king, 82, has moved to reassert his authority in the wake of Khashoggi’s killing in the Saudi consulate in Istanbul last month, which has created the biggest crisis for the country’s leadership since the September 11 attacks of 2001.

Attempts to build national unity in the face of a diplomatic storm over the Khashoggi case underline the growing role that the king is playing in the aftermath of the killing, which is being blamed on individuals close to his son, Crown Prince Mohammed bin Salman. “The king is caught in a situation,” said one western official. “He has entrusted his son to carry out a transformational process, which he doesn’t want put in jeopardy by a bad mistake.”

The announcement came as Turkey’s vice-president said that Khashoggi’s remains may have been disposed of using acid, as he demanded that Saudi Arabia turn over suspects in the investigation. “There is talk that he was dissolved with acid. All of this must be cleared up,” Fuat Oktay told the state-run Anadolu news agency on Monday. “We want [the suspects] returned, we want to try them here.” Khashoggi’s body has not been located, even after a Turkish forensics team searched the Saudi consulate and the consul-general’s residence in Istanbul.

He was last seen entering the Saudi consulate in Istanbul on October 2. Saudi Arabia initially denied involvement in the killing, but has since acknowledged Turkish evidence that the operation that ended in the journalist’s death was premeditated. About 18 people have been detained in the kingdom in connection with the incident, which Turkey has blamed on a Saudi hit squad. Riyadh has denied that Prince Mohammed was involved, saying those responsible will be held accountable.

Prince Mohammed has had an inexorable rise to power since his father took power, with increasing control over economic reform, oil policy, foreign affairs and domestic security. The return of a senior prince from self-imposed exile and the release of a jailed royal recently have sparked speculation that the royal family may be forced to accept curbs on its domestic agenda by releasing critics imprisoned last year and restoring freedom to royals and businessmen caught up in the fallout from last November’s anti-corruption crackdown.