Yes, I’d say Martin was a schizophrenic. What he imagines himself to be and what he really is, reality dictates the rules.
Martin was awkward too. The drug he injects was slow acting and physically, Martin was barely capable attempting to overpower his victims from getting the better of him. It is more disturbing that he succeeded in what he was doing, even though it didn’t quite work out like he would have envisioned - “Just go to sleep.”
Norman! What did you put in my tea?

Because he isn't. Martin is clearly nuts.
You've seen Guy Standeven in something because the man was in everything.

Well the first black and white sequence happens on the train just before he opens the door to his victim's compartment. He imagines her in a nightdress, welcoming him. When he actually goes through the door things play out very differently. If the very first black and white segment is shown within seconds to be false and merely Martin's fantasy then I'd say all the others are fair game for similar interpretation.

I like to think that he is in fact a vampire. But honestly, there's really no evidence to prove he is maybe he is just a murderer and his cousin is as crazy as he is? I think it's purposefully left up to the viewer to decide.

I don't get it either. They say the black and white shots are what he imagines things to be but to me I think they're back when he was younger and in another land, maybe Europe? I think he's a vampire but he just doesn't wanna bite people on the neck, and of course he can't turn into a bat etc. This movie is so amazing and I wish more people knew about it. Maybe we will get a Blu-ray released one day.