If a particular person keeps breaking things by skipping code reviews and such then you may already have a toxic environment. That person needs to be talked to, not necessarily chastised, but talked to for sure.
Ahhhhhh!!!! Skipping code reviews is asking for breakages! And it's not even that person's fault, if the broader team allows unreviewed coffee to be checked in.
Of course, one of the other great things about code review is that it diffuses blame, and allows us to focus on other things. If Dev A introduced a bug even after Dev B reviewed the code, then the root problem isn't that Dev A is a dummy.
One needs some openness to changing process to prevent future bugs; process questions are a key part of a postmortem.
