Yes had the crime scene been staged as a home invasion, the victims appearing as if they’d tried to prevent it, or at first glance, posed in their beds as if they’d died in their sleep from an accidental cause such as carbon monoxide or overdose, the crime scene might not have appeared quite so blatantly shocking.
But for the couple to be staged in an self-admitted execution style manner at death, I’m not so sure it’s a warning by the perpetrator for others to stay silent as much as it was to inflict horror, humiliation and shame upon the victims and the Sherman family, with the intention the death would never be recognized as anything beyond m/s. I wouldn’t doubt if the scene was staged also by other means to support that conclusion. Why else would’ve the m/s rumour began in the first place?
