First you will notice that West is looking into Clair's window, not with an in-love look, but a rather devious one. Notice he is wearing a blue hoody unzipped with the hood down (you can see the hood when he flies away).
The next clip is Hiro's dad on the roof and who shows up? A guy in a blue hoody zipped up with the hood up, and their body build is about the same. He hits Hiro's dad off of the roof and they both are shown falling off, but then only one body is found on the ground. Did the other fly away?
Is this proof that West is the killer? Is west also somehow connected to Nathan since they both can fly? Did Nathan send West to watch Clair? Did Nathan put the picture outside of the apartment with his mom's picture on it on the his way in? Did he also put the picture into the newspaper that Ando was holding when he bumped into him?
Scene:
http://youtube.com/watch?v=QR8hUZ0rY4I
If he is just a normal kid then what's he doing spying in Clair's window? How did he find out where she lived, did he follow her there too? That's stalking. And the devious look when he asked are you one of them? He saw her with her hand in the fire, and acted like it was no big deal. Doesn't it seem like he knows her already?
The fact is someone most likely flew away from the scene. If it was a healer like Clair, there would be blood from the hit, and it takes time to heal. So who can fly? 3 people: Nathan, West, and Peter. The build was too small to be Nathan, and it seems too obvious. Peter don't even know who is he is right now, and he's locked up in a crate. It's the best fit from the known characters.
For those who mention that West is in California and Kaito is in New York, we do not know how fast West can fly, nor how much time actually elapsed between scenes. And don't forget the time difference. And why did he walk up the building instead of fly? Because if he flew there would be no mystery at all!
"I never expected it to be you" Perhaps because he is so young? - Seems he's not the only one who never expected it.
Could this be West or a stunt double for him? Decide for yourself.
For reference, here's the original:
http://www.nbc.com/Heroes/photos/sea...23.shtml#photo
UPDATE:
The picture of Clair's dad dead also had a picture of Clair kissing West. The lover and the killer.
The bullet in his eyeball means it was not done by some power.
http://img3.freeimagehosting.net/ima...c96cc0ccc0.jpg
Obviously the painting does not show Clair Kissing West while in the same room as her dad is dead on the floor. So the fact that both scenes are in the same picture means they are related somehow. Hence, it lends credence to the idea that West is the killer.
The slits on his neck may mean he was controlled to do it.