One cannot disagree with the principle of innocent until proven guilty. But the accused has, before coming to trial, to explain their proximity to whatever crimes they are alleged to have committed. Failure to do so convincingly leads to prosecution. During the trial the principle of innocence applies.
In the case of Saudi Arabia, the journalist enters the consulate and fails to emerge. Up to fifteen Saudi security agents are known to have entered the building including a post mortem doctor armed with a bone saw. Recordings apparently exist of Mr. Khashoggi’s interrogation, torture and death in the consulate. There is even more we are not being told. The Saudi Government must explain all this. Denial is not enough. Until it can prove all these things did not happen, or happened without its authority (insiders say that notion is the most implausible of all), the Saudi Government remains a suspect. In fact the only one.