As a general ethical principle, we are each responsible for our acts and the degree to which these harm or benefit others.
Insofar as it could be shown that someone produced or did something that was foreseeably harmful -- and that will be the sticking point -- it can be argued that they are responsible for the harm caused. This can include situations that might be called negligent, in that the person did not know or anticipate the possible harm, but should have.
Such situations are more common than we might like to admit.
The legal ramifications of such a circumstance are another matter. I'm only speaking to the basic (philosophical) ethical principles that one would generally employ when someone has been harmed by another person's choices.