"Suppose I pour poison in the water tank of a space ship while it stands on earth. My purpose is to kill the space traveller, and I succeed: when he reaches Mars he takes a drink and dies. Two events are easy to distinguish: my pouring of the poison, and the death of the traveller. One precedes the other, and causes it. But where does the event of my killing the traveller come in? The most usual answer is that my killing the traveller is identical with my pouring the poison. In that case, the killing is over when the pouring is. We are driven to the conclusion that I have killed the traveller long before he dies."I'd argue it's not murder until the astronaut dies. Here's why ...
Imagine that it is murder at the moment the poison is introduced to the water, you conduct a speedy trial, gain a conviction, and execute the murderer all in the same day -- for our purposes, justice is swift. Then, the astronaut, only a day into his journey, finds a fault in some equipment that necessitates an abortion of the mission and a return to earth. He lands safely having forgone drinking from his ship's water supply. The astronaut lives another fifty years. Was your murder conviction just? Of course not.
A more interesting question is: what if the spaceship explodes en route, and we never learn why. Nor do we know if the astronaut drank some of the poisoned water before the ship exploded. But, we have a last transmission that ends, " ... I'm thirsty, I'll resume the mission log in a minute." We discover the poisoner's deed. Is it attempted murder, murder, or something else?
Or, what if the astronaut learns the water is poisoned, doesn't drink it, starts to become ill, but makes it to Mars only to die in a crash landing caused by mechanical failure ... that he may have been able to fix had he been at full strength?