Who was accused of the crime? Why was he eventually set free?

Victor is brought before the magistrate accused of killing his best friend. The magistrate visits him and expresses confidence that he will be cleared of all responsibility for the murder. He tells Victor that "a friend" has come to see him; thinking that it is the monster, Victor begs to have him sent away. Mr. Kirwin, much taken aback by this outburst, sternly informs him that the visitor is his father; at this, Victor is overjoyed.