I think my neighbor is a vampire how can i make sure about it?

he has a sharp and white teeth and he also is single and livin alone.and well i never saw him in daylight im sure somethin is wrong with this guy cause he always smile in a weird way i watch so many horror movies i know he is not human,should i suddenly stab him in heart or i hav to kill him in coffin?(im 100%serious about this)thnx