Based on David's case, it is possible to assume that he had undergone a significant change in his behavior, as he went from being a passive and mild-mannered person to someone with a bad temper who lashed out at family members. This change in behavior could be due to a variety of factors, such as stress, mental health issues, or substance abuse.
Regarding David's responsibility for his crime, it is difficult to say. The prosecution argued that he had lost his temper and murdered the client in a fit of rage, but there may be other factors at play, such as mental illness or diminished capacity.
The fact that David was reported to be acting "out of character" in the days leading up to the murder is significant, as it suggests that there may be underlying issues that contributed to his behavior. However, it is important to note that this alone does not absolve him of responsibility for his actions.
In conclusion, David's case highlights the complex nature of criminal behavior and the many factors that can contribute to it. While it is important to hold individuals accountable for their actions, it is also important to consider the broader context in which those actions occurred.