There is an unrelated report of an attack by the neighbor prior to this one, known to the association board. There is reason to believe the neighbor is suffering significant bouts of rage.
That is the thought that keeps coming to mind: no way some Doctor just suddenly runs across the yard and hammers a neighbor. Peel this guy back some, look into his history and I’d bet you a cheese-burger there is a trail that puts his actions in context. There were warning signs before this happened.