Perhaps the Reiners could have hired a bodyguard-slash-nanny for their son?
It seems they were quite aware that their son wasn't capable of taking care of himself. Whether they also realized that he could harm others, well in retrospect now that's an obvious statement. They surely loved him and wanted to look out for him, but perhaps they didn't understand the inherent danger of caring for a drug addict who also has mental issues.
I'm trying not to be judgmental in this family tragedy.... My own family has dealt with similar mental issues in more than one of my siblings. We've recognized that sometimes the answer is institutionalization, when the safety of the victim and others is concerned. The Reiners were in a position to afford private mental health caregivers (nannies). Such a gesture might have saved their lives.
