Need Help Finding A Film ? Anyone Help?

The end is based in a prison, the only thing i really remember is at the end the main character puts the american flag upside down to say he surrenders and all the prison guards put their guns down. But the warden takes one of the guards pistols and kills the main character. Don't Suppose any of you know what its called ? If i recall correctly the warden is quite a chubby guy. I was young when i watched it so it must be based around the 90's. Its not The Shawshank Redemption.