Yes, they do need to be saved again. Jesus died for all of mankind's sins, but an important part of the process is that they accept Christ's forgiveness. This is more difficult than most people realise, because true forgiveness isn't just asking to be forgiven, it is acknowledging that you have sinned, acceptance that the sin was immoral, regret that you committed the sin at all, and the decision to turn away from that sin. Of course, this is assuming that he finds out about Christianity. If he has not heard the teachings of Christ, then the only sin he is guilty of is ignorance.