This article discusses the issue of differential diagnosis of cases of suicide that are prompted by the murder of another person or persons. Long-standing use of violence by the perpetrator against the victim motivated by jealousy, will of revenge, hatred, a desire to physically hurt another person, and a desire to brutally kill another person quickly and in a cruel manner indicates that we are dealing with a post-aggression suicide, and not an extended one. Extended suicide has been defined as being motivated by altruism and as a result of deep mental disturbances as well as a transference of one’s problems onto close family members with whom the perpetrator is emotionally involved. Authors suggest that the true differentiation between “post-aggression suicide” and “extended suicide” may play an important role in forensic psychiatric opinions conducted at the request of law enforcement agencies and the justice system.