When you say "universal", do you mean just among human communities, or do you mean among any community of sentient beings?

Because I think as soon as we accept the theory of evolution, then it becomes apparent that humans don't have a monopoly on sentient value-making or moral norms.

And so if we claim a moral law to be truly "universal", we have to mean that it is wrong for any sentient being to kill any other sentient being.

But I don't think that's a stance we can logically take, because I don't think it makes sense, for instance, to declare it morally wrong for a predator animal to kill a prey animal. The universe sometimes pits different sentient perspectives against one another, and we can't really do anything about that, other than accept the rule of "survival of the fittest".

On the other hand, if by "universal", you just mean, "within generally democratic human communities with enough food to go around", then yes, probably murder will always be a violation of the community's expectations of its members.