What is the protest about? Unless the situation of the protest clearly defines the "murder", the sign just says "I don't like America." It draws away from the message of the protest. It makes you look like a professional protester, who doesn't care about the specific issue, but just want to yell. I sound harsh, but you asked for opinions. A more focused message would be better. The proposed sign requires an explaination for someone to decide if they agree with you. You won't have the opportunity to explain the sign to everyone who sees it.
