I'm not familiar with the term "Excusable" Homicide. Justifiable Homicide occurs when it is ruled (usually a Grand Jury) that a death of someone was proper and occurred within the bounds of law (i.e.: the shooting death of an armed bank robber by a police officer).
A co-felon is not guilty of felony murder where the killing constitutes a justifiable or excusable homicide. Such would be the case where, for example, the police or a Victim shoots one of the co-felons, but not where the killing is done by one of the Felons.
valid, plausible, justifiable, tenable, logical, permissible, excusable, defendable
If the homicide was justifiable then no criminal act has been committed
The cast of Justifiable Homicide - 2010 includes: Herb Cremer as Herb Joseph Cremer as Joe
An example of justifiable homicide might be if you were attacked by someone and in fighting them off you killed them or somehow caused their death. Felonious homicide would be when you planned to kill someone, or your actions were such that death could be presumed to be the outcome.
Homicide is the killing of another person: straightforward. The degree of homicide can range from justifiable homicide to capital murder. This is all determined by the facts of the case.
And what is your reason for asking this question?
The term "murder" means a premeditated or preplanned killing of another person. You may be thinking of unintentional homicide, which could range from manslaughter by culpable negligence to justifiable homicide. In the case of the latter, the person must be committing a lawful act in order to claim justifiable homicide - self-defense or accident. He could still be charged with homicide by culpable negligence.
"Murder" is illegal. You'd have to convince a jury that it was "justifiable homicide" and there was no other choice.
Vanial is not a word. You might have meant Venial, which means able to be forgiven or pardoned; excusable.
Late arrival for a job interview is never excusable.
A very small percent of people are killed by justified homicide with guns. Most deaths by firearms are deliberate or inadvertent.