Let's start with a thought experiment. Suppose I push you into deep water as part of a swimming lesson. Because you do not know how to swim, you start desperately trying to keep yourself afloat, but to no avail. Now suppose further that I do nothing to rescue you, and as a result, you drown. My actions in this scenario are tantamount to murder. I intentionally placed you in a situation of great vulnerability and then refused to provide for you. Your rights were egregiously violated by my refusal to do anything.
The moral principle behind this thought experiment is the following: if I knowingly cause you to exist in a state of great need or vulnerability, then I am responsible for providing for you. If I do not, then I am negligent. If my negligence leads to your death, then I am guilty of murder.