Rose's Gal - you are right when you say a murderer/rapist would'nt be a follower of Christ, because his actions would be good and pure and not evil and harmful if he was a true follower.
I do believe that someone can become a believer after a terrible act, many do find God after they are sent to Death Row, and if they ask for forgiveness, they will receive it. I know that is hard for a lot of people to understand, how someone so evil could go to heaven, but the beauty of it is - you can't fake it. God would know your true heart, and if you were truely repentive, yes you would be forgiven.