There is no excuse for his crimes, but I also suspect Godbolt had no fully conceived plan to commit as much mayhem as he did.  Pehaps due to a skewed way of thinking and also if you add a warped notion of self-respect, the arrival of the deputy may have been taken as a personal affront to his dignity and as the proverbial "last straw."

Having known of others who have met similar ends, what is also a common thread is this:  if they survived long enough to explain themselves, most stated something that amounted to, "After I killed the first one, then killing the next one and then all the rest became easier and easier."