Turkey has charged 20 suspects over the murder of the Saudi journalist Jamal Khashoggi in Istanbul in October 2018.
Prosecutors said an indictment accused former Saudi Deputy Intelligence Chief Ahmad Asiri and former royal aide Saud al-Qahtani with instigating the murder.
The 18 others are accused of carrying out the "deliberate and monstrous killing" inside the Saudi consulate.
Western intelligence agencies believe it was ordered by Crown Prince Mohammed bin Salman – something he denies.
- The secret tapes of Jamal Khashoggi's murder
- Jamal Khashoggi: All you need to know about his death
A United Nations special rapporteur says Khashoggi was "the victim of a deliberate, premeditated execution, an extrajudicial killing for which the state of Saudi Arabia is responsible".
At the time of his death the 59-year-old worked for the Washington Post and had become a prominent critic of the Saudi government.
Saudi authorities blamed a “rogue operation” for Khashoggi’s death. In December, a court in the kingdom sentenced five unnamed people to death and jailed three more over the murder.