Chapter 7: Victor gets a troubling letter from his father, which says that a tragedy has occurred at home: little William has been murdered. Apparently Elizabeth has taken the news very hard. "She weeps continually," Mr. Frankenstein laments. Victor's heart sinks, and he decides to leave promptly for Geneva.
Near home, during a thunderstorm, Victor is startled to see a large figure peering at him through the dark trees of the forest. He explains, "A flash of lightning illuminated the object, and discovered its shape plainly to me; its gigantic stature, and the deformity of its aspect, more hideous than belongs to humanity, instantly informed me that it was the wretch , the filthy demon, to whom I had given life." It's at this time that Victor realizes that his monster is the murderer. He finishes his sorrowful trip home, burdened with a guilty conscience.
Upon his arrival, Victor hears more terrible news: Justine, their adopted child, has been accused of killing William. This confuses everyone, especially Victor, because he believes that his own creation is the perpetrator, though the evidence seems to point to Justine.
Chapter 8: Justine's trial takes place in this chapter. Apparently the girl is missing the whole night of the murder, but the most damaging evidence is that she is found with a certain picture in her pocket which all but proves that she is the murderer. Elizabeth gave this picture to William just before he left to go on his fateful walk in the forest. Justine is unable to explain how she came to possess the picture.
The morning after the trial, Victor hears that the young girl has confessed that she is indeed the murderer. When he and Elizabeth question her about it, Justine admits that she did confess but that she "confessed a lie." This only troubles Victor and the others more, but nevertheless, Justine is executed the following day. Victor is guilt-ridden beyond belief, telling Walton that William and Justine were the "first hapless victims" of his "unhallowed arts."