As Pi remarked earlier it is doubtful that Ranma - Neko is the killer for
indeed he/she does not posses the intelligence of disposing the body.  But
that does not terminate him/her from the suspect list, to further elaborate
he might have an accomplice that disposes of the bodies for him
(Gosunkugi?).  The other theory, that someone is trying to frame Ranma by
using Neko-ken as proof is also plausible, but to pull it off they have to
convince the police that the Neko-ken does exist and that Ranma knows how
to pull it off.  


"Curiouser and curiouser..."
-Alice 
 Alice in Wonderland
A hero is someone you can look up to 
without appology