hmm thinking of apotoxin angst. conservation of mass would dictate that conan either be denser than shinichi, or that whatever wasn't used in the transformation is sloughed off and cast aside.
in fact, I'd like to think that the Perfected apotoxin would slough everything away into water or something innocuous, decomposing the human body into its base elements reverse fullmetal alchemist style.
but, it doesn't work on shinichi. and so in that amusement park, conan is born from within him, having to cast of the remains of his old body like an amniotic sack. thinking of the police, finding Shinichi Kudo's incomplete, desecrated corpse and searching and searching to find The Rest. not knowing that it's Conan.
thinking about conan needing a certain amount of biological mass similar to his own nearby in order to become shinichi again. needing to deface, desecrate, destroy the body of a victim in order to unmask their perpetrator as Shinichi.
