Last murder was different...why? SPOILERS!

Ok...I just finished watching the movie and I really liked it!! Just like everyone else I wanted to find out who the murderer is but there seems to be no correct answer to this. So that's okay with me since the murderer in the real case that this movie was based on was never found either.
But...what I can't understand is why the last murder in the movie was different from the others?
I mean, was it different for some specific reason that I was supposed to understand but didn't?
I checked some different threads about this movie but couldn't find anyone that brought this up.

The thing is that during the last murder it wasn't raining and the victim didn't wear any red clothes...at least not that I could see.

It made me wonder if this was intended so we were supposed to figure out the last pieces of the puzzle.

Just want to know what you think about this and if there is a specific reason behind it all?



Don't we all become detectives ourselves when we enjoy a mystery like this ;)