In my CS program we had an ethics class that included stories of bad X-ray machine software that overdosed people. Bad, bad bad. I don't think many people died as a direct result, but 10 years later there was probably a spiked cancer incidence. Did software kill people? Well yeah....kinda.

In airplane systems, there have been a number of cases where bad alerting / warning systems basically either misled the pilot or lulled them into a false sense of security prior to events that caused crashes. Did software kill people? Uhm, yes, I think, sort of, but not directly?

It's only when we get fully sentient AI that arms itself and decides to clean up the human pestilence that we'll be able to draw a straight line there. :)