1. He is guilty because a fair court has held him guilty (and we must understand that the court is the competent authority to have looked into evidence and take a balanced judgement on the issue)
This is not to say that we must not improve the system but that we must accept the outcome of the system (which sometimes may be at variance from what we believe)
In nutshell - yakub's case was fairly tried and a considered judgement made. One hopes that was the case in every such case.