One of Matt Murdock's key personal rules is that he never kills anyone, even if they deserve it. This plays a big part, for example, in the Netflix series Daredevil, where he struggled over his decision to kill or not kill Kingpin, but this aspect of his hero persona is present in every incarnation I am aware of.
However, he seems to have very little problem beating the hell out of anyone who gets in his way, including people who haven't committed a crime. As badly as he tends to beat people, I can't imagine that not a single one of them has ever died from their injuries.
All it would take was an errant cracked rib puncturing the lungs, or severe internal bleeding, or damage to a kidney or liver. Even worse, Murdock knocks out countless low-level thugs long enough to fight off the rest of their crew, rescue hostages, have long chats with dirty cops, etc. If someone is rendered unconscious via head trauma, and doesn't wake up very quickly (second to minutes), at best they're going to suffer permanent brain damage, and possibly won't ever wake up.
Has there ever been a case where Murdock inflicted lethal injuries on someone, without intending to, and we (or even better, he) found out about it?
(N.B. I'm assuming he has never purposefully killed someone, but if he has, that's not what I'm asking about here.)