clinical proof, better said: clinical evidence or clinical confidence, is based on patterns of mind plus behavior plus functioning over time, not just on crimes and not just on fantasies alone.
Psychiatrists diagnose mental conditions, not evilness or criminality.
What is it based on.
Usually a combination of:
Observable behavior,
What the person repeatedly does.
Examples are chronic lying, manipulation, aggression, impulsivity, lack of remorse, unstable relationships, grandiosity, violati