Not a CEO, but I'm reminded of the incident on a Navy vessel that struck a fishing boat and resulted in a number of fatalities. The captain was actually off the vessel at the time and not in charge. He still resigned because he was accountable to the decision on who he left in charge.

(Tbf, I'm sure he was told to resign. But that's largely because the Navy has tried to institute a culture of accountability, albeit imperfectly)