Presumption of culpable mental state shifts burden to accused to prove absence, with facts proved beyond reasonable doubt. The amendment creates a rebuttable statutory presumption of culpable mental state in prosecutions under the Act, defining culpable mental state to include intention, motive, knowledge, belief or reason to believe; it makes it a defence for the accused to prove absence of such state. The section further provides that a fact is proved under it only when the court believes it exists beyond reasonable doubt, not merely on a preponderance of probability.