based on what we know now, I don't think so.
but anyone can alter their handwriting, so this is not the definitive piece of evidence.
look how fast the Thai police backed off all of the reports about him saying that he drugged her, picked her up from school, etc. all of the disqualifying stuff from yesterday, they withdrew today.
I still think it comes down to:
DNA
prove he was in Boulder and not someplace else that day
how did he know the Ramseys
explain the issues regarding what he would have had to do entering and while inside the house to commit the crime
I agree.