Pics of the killer were everywhere before they caught Luigi. He had plenty of time to write the manifesto, find close (but not same) clothes, find gun and find close (but not same) backpack...
I dont know why he tried to make himself look like the killer. But what is undeniable is that he is not the killer, and there is a clear and reliable proof: pic of the killer is not him, not the same upper face, not the same height and not the same body frame. Saying otherwise is at the same level of stupidity as flat eather...
Now show us the same graph, but going back to first hominidae.