Preparatory instruction must include both guilt and innocence evidence to ensure fair trial balance.

The court ruled that the preparatory instruction must encompass diligences proving both the accused's guilt and their potential innocence or irresponsibility. The prosecution argued for limited investigation focused solely on establishing criminal liability, while the defense contended that a comprehensive inquiry into mitigating factors was essential. The court decided that excluding evidence of innocence or irresponsibility would violate the fundamental principles of a fair trial and the duty of the investigating judge to gather all relevant facts.