You will not prevent the next accident by studying the last accident. I know this idea is incredibly appealing, in fact most organizations tell me they are fixated in making sure they "never have a repeat occurrence." The quickest answer to this idea is to simply state: "You will never have the exact same event twice."
What seems most important is the power of small signals that indicate an increase in safety threats to a stable system. Weak signals are everything - and yet we often move as leadership teams in to a type of "collective neglect" about the power of a weak signal.
Listen carefully to your organization. Those weak signals can (and will) tell you much.