Answer:
Mental Health Deterioration
Violent Murder: Homicide against another human being. Lack of empathy and remorse in the act, usually cruel.
My guess would have to be that some people don't have access to mental health facilities to evaluate when someone could be considered dangerous. Usually someone will show red flags or warning signs if they are considered hostile, but this isn't always the case. Therapy and Mental Health aren't always prioritized by many civilians or the like, and therefor problems aren;t able to be identified when they need to be. With modern advancments, come modern problems. Hope this helps.