Marshall Scott/Ethics
Hunting:
He likes to consider his victims parasites on society and that removing them is a public service. Being a cop for so many years means that he's still out there to protect people from the 'monsters' on the street - even if that means becoming one.
Killing:
Marshall only kills when he needs to feed. Since he hasn't quite got the hang of being able to take small amounts or to seduce his victims, he ends up killing them. The good news is that this means he's able to feed from them over several days. The bad news is that he's killed someone and has to deal with the body - and the psychological ramifications.
Immortality:
His embrace came out of the blue - something that was done to him when he had no knowledge or consent. It was, essentially, a form of rape. He never knew the woman who embraced him and therefore never learned anything from her. It is a twisted sense of irony that only a week before his mortal life ended that he discovered a tumor in his chest. It was small but it was in his lungs. Never having really smoked it would have spread throughout his body and killed him slowly - if he had lived. Now immortal, or as close to it as vampires can achieve, he can live out a long and 'healthy' life.