Necrophilia
Necrophilia is an unnatural attraction towards dead bodies, it is a perversion that causes considerable disgust for obvious reasons - although some necrophiliacs are murderous most do not actively seek to murder others, instead they may resort to grave-robbery or breaking into morgues and similar places so as to fulfil their fantasies, for some Necrophiliacs the simple act of laying next to a corpse is arousing while others may feel the need to mutilate or abuse the corpse in ritualistic ways.
Necrophilia is usually a sign of deeper mental health problems, though not always.