In chapter 7 of Mary Shelley's Frankenstein Victor has been away from his native home for years before he receives the horrible news, by a letter from his father, stating the tragedy of young William's death.
This is a shock to Victor because he realizes that he can no longer put the creature out of sight and out of mind. The creature is very real and is obviously on a mission to destroy Victor and his family. For this reason, Victor is particularly sickened by this later event: He simply cannot do anything about it, but suffer through it and endure what could have been.
However, there will be more: Justine Moritz, the adopted young girl of Elizabeth's family is accused of William's murder only because the locket for which William is presumably killed is found in Justine's pocket.
It is later in chapter 8 when we find the actual trial taking place and Victor, ever more guilty and wretched than ever, contemplating his ambition as the causative factor of such a family disgrace:
During the whole of this wretched mockery of justice I suffered living torture. It was to be decided, whether the result of my curiosity and lawless devices would cause the death of two of my fellow-beings: one a smiling babe, full of innocence and joy; the other far more dreadfully murdered, with every aggravation of infamy that could make the murder memorable in horror. Justine also was a girl of merit, and possessed qualities which promised to render her life happy: now all was to be obliterated in an ignominious grave; and I the cause!
It is interesting to point out how deeply Victor is affected by this trial, for it is more a trial for himself and his own evils than it is a trial for Justine's possible involvement in the murder of William. It almost seems as if Victor is more affected than anybody else. Even Justine, herself, does not seem as miserable as Victor.
My own agitation and anguish was extreme during the whole trial. I believed in her innocence; I knew it. Could the daemon, who had (I did not for a minute doubt) murdered my brother, also in his hellish sport have betrayed the innocent to death and ignominy? I could not sustain the horror of my situation; and when I perceived that the popular voice, and the countenances of the judges, had already condemned my unhappy victim, I rushed out of the court in agony. The tortures of the accused did not equal mine; she was sustained by innocence, but the fangs of remorse tore my bosom, and would not forego their hold.
Therefore, what this tells us is that Victor can be capable of remorse because he is not inherently bad. He simply gets carried away by ambition in the story and, due to this sudden obsessive hunger for success and for imitating God, he digs his own grave of torture and misery for the rest of his life.
Victor feels guilty for the death for Justine because he didn't confess to his creation doing these things