IMO, the board of a public company is responsible for overseeing risk, audit and internal controls, and the CEO is the one person most responsible for ensuring the company acts in accordance with those directives on a day-to-day basis. That an error could be made by a worker is human, though an automated system could also suffer a fault. Audit would have caught a gap, risk management would have caught a vulnerability, and internal controls would have detected incomplete work were these practices properly designed and deployed. Good CEOs look at governance, process, oversight and don't fling muck at employees.