Learn to ask what made the problem possible before asking who made it happen.

Who did it is a narrower question than what made it possible. There is nearly always a person involved, and finding them ends the inquiry early, while the conditions that allowed the harm stay in place waiting for the next person. Both questions have answers; only one prevents a repeat.

After something goes wrong, ask the structural question first and the personal one second. It lowers the temperature, gets you more honest information, and tends to produce a fix that outlasts the individual involved.