I'm a doctor, not a lawyer, but AFAIK "homicide" is a legal term that means "wrongful death" or something similar. Not the same thing as "murder." Drunk drivers get charge with "criminal vehicular homicide" without malicious intent; it amounts to criminal stupidity. I think "negligent homicide" applies to taking an action that leads to someone's death, knowing that it was dangerous but without the specific intent to cause harm; something like firing a gun blindly, not realizing that there was a person hidden from view but in the line of fire.
You wouldn't happen to be the same ER doc who edits on Wikipedia, would you?