Mueller did not bring this indictment. He presented the evidence to a Grand Jury of your fellow citizens. Those fellow citizens saw enough evidence to convince them to return the indictments.

If the individuals indicted ever stand for the crimes they are alleged to have committed, then we will see the evidence as it will be a public trial albeit with any evidence that will reveal national security secrets redacted from public view.

This is exactly how our justice system is supposed to work.