DW: How did you reach the conclusion that there is "credible evidence" that Saudi authorities were involved in Khashoggi's death?

Agnes Callamard: The first important finding of my inquiry is about the responsibilities of the state of Saudi Arabia. Until now the Saudi authorities have insisted that this was not a state-sanctioned crime but a rogue operation.

What my report shows is that the killing of Mr. Khashoggi meets all the criteria for a state crime. It was conducted and done by state officials. It used, it relied upon state means and state resources. The team that came to Istanbul used a private jet with diplomatic clearance. The killing took place in the Saudi consulate. The Saudi consul himself took action so that there were no witnesses on the day at the time of the killing.

Read more: Jamal Khashoggi: A mysterious disappearance and death

This and other evidence presented in the report mean that there is no other conclusions but that the killing was what we call a state killing.

If it was a state killing done by state officials as your report found with state resources, does that mean that Crown Prince bin Salman is responsible or liable for the killing of Khashoggi.

My investigation is a human rights investigation focusing heavily on the responsibilities of the state. In that context I have considered individual liability only to identify whether or not there was in my opinion sufficient credible evidence mandating an international criminal investigation.

My conclusion is that on the basis of what I have found and analyzed there is indeed credible evidence demanding a criminal investigation into high level officials including the crown prince [Mohammed bin Salman].

What I also want to insist upon is that the possible liability of the crown prince is not only derived from whether or not he ordered the crime — the search for a smoking gun is important but it is not the only form of responsibility for a high level official within a civilian setting. There is something close to a chain of command and a range of responsibilities associated with it.

Read more: 10 most urgent cases of journalists under threat: June 2019

For instance, did the crown prince or someone else directly or indirectly incite the killing of Mr. Khashoggi? Did the crown prince or someone else know about the proposed killing but failed to take action to prevent it? Did the crown prince or someone else know or should have known that the killing of Mr. Khashoggi was a possibility in light of the multiple violations of human rights that had taken place in the year preceding this killing. All of those issues must be the object of an in-depth criminal investigation.

Where should this criminal investigation take place and what should the jurisdiction be?

My recommendation is that the international criminal investigation be conducted at the level of the United Nations; I call upon the secretary-general to appoint a panel of experts that will look into individual liabilities on the basis of the evidence.

Agnes Callamard is political scientist with a focus on human rights. She has been the UN's special rapporteur on extrajudicial executions since 2016.