Some believe that murder is only committed due to an emotional or moral action, but can you ever justify it with reason?
Yes and no.
This question yearns for the comparison between two views:
Moral Absolutism and Consequentialism.
Moral absolutism is an ethical view that certain actions are absolutely right or wrong, regardless of other contexts such as their consequences or the intentions behind them. Thus stealing, for instance, might be considered to be always immoral, even if done to promote some other good (e.g., stealing food to feed a starving family), and even if it does in the end promote such a good.
Consequentialism is the class of normative ethical theories holding that the consequences of one's conduct are the ultimate basis for any judgment about the rightness of that conduct. Thus, from a consequentialist standpoint, a morally right act (or omission) is one that will produce a good outcome, or consequence.
These two contrasting views dictate what you may and may not do.
While Moral Absolutism is only with respect to the barebones of one's actions (and cares about nothing else), consequentialism takes into account the final objective/result that one strives to achieve.
Let me give you an analogy:
Imagine you have committed a crime, and thus, you are now on trial. You are given a drink that forces you to only tell the truth when prompted.
Scenario A (Moral Absolutism):
The judge asks you whether you committed murder. You respond by saying, "yes". The judge then immediately sentences you to 25 years in prison.
The judge does not know (and does not care) that you were abducted, kidnapped, and tortured, and that the only way to escape was to kill your captor while he was distracted, take the keys from his pocket, and unshackle yourself and escape.
Scenario B (Consequentialism):
The judge asks you whether you committed murder. You respond by saying, "yes". The judge further asks questions to find out why you committed the crime. He finds out what the true reasoning the murder was and thus, merely sends you to a rehabilitation center to prepare you to re-enter society.
Hopefully, these analogies gave you an idea of each view.
Each view has its pros and cons. Of course, scenario A was fairly unjust (no pun/oxymoron intended) because the basis of the deeds was not taken into account. But on the other hand, consequentialism can also be twisted to reflect Machiavelli's "The ends justify the means" and be taken advantage of.
Many questions come on the borderline and are difficult to answer such as killing one innocent person to save a thousand.
The ultimate answer to your question lies with your decision of which view you believe to be the most suitable for the situation.
No. Murder cannot be justified through logic, reason, emotion, or any other means. If it can be justified, it's not murder-- it's justifiable homicide, or manslaughter, or an act of combat, or self-defense, or capital punishment, or euthanasia, etc.
Now, if you are asking if homicide can ever be justified, the answer is obviously yes. It is almost universally accepted (across cultures and ethical systems) that there are some circumstances where the killing of another person is justifiable.
This sort of question is easy. It is always justifiable to murder in order to prevent two murders, all else being equal.
Yeah. It isn't a special or unique action. It is moral if it makes no one's life worse. And it won't make the victim's life worse, as they will be literally incpable of caring.
Psychopaths may say that only their lives matter. Truly, the most logical standpoint. But I have empathy, so it is not valid for me.
Murder is illegal killing : killing another person with the intent to kill, with the conscious objective of killing. (This is the everyday sense; I cannot do full justice to legal precision.) Only on a tight connection between law and morality can murder be unjustified merely because it is illegal.
So we have to start again. There can be at least one perfectly logical reason for killing someone, namely that it is helpful to my purposes to do so if they are blocking some intention or goal that I have. I do not suggest that this would morally justify killing them but it would be rationally and logically justified - justified by means/ end rationality.
It may also be logical or rational to kill someone if on a careful sekf-interested or altruistic calculation this is the only way to prevent their causing, or continuing to cause, disastrous harm to others. This could have a moral justification as well unless one subscribes to some such principle that it is always wrong to take a human life, whatever the consequences.