Acts 9 the story totally changes. In Acts 9, Saul is confronted by Christ and is stricken blind by the very person he has been persecuting. In the greatest sense of irony, the most aggressive persecutor of the church is God's chosen man to be the missionary to the world. Saul is taken to Damascus where he regains his sight and is baptized into the very faith he had sought to destroy. Over the rest of his life Paul (he changed his name, common in the Bible to show an identity shift, Jacob to Israel, Abram to Abraham, Sarai to Sarah), travels throughout the Empire and to the Eternal City itself to preach Christ and to be a witness to Him in the marketplace, the church, the synagogue, and the center of the known world. Paul's family heritage, his education, and his standing as a Roman citizen are all used by God for the purpose of spreading the Gospel to the world.
Paul is no longer Saul, this man who breathed murderous threats to the church and executed (indirectly, he would be unclean to touch a corpse), is dead. The one who lives is Paul, and this takes on a whole new meaning when you look at 2 Corinthians 5:17 where Paul says that those in Christ are a new creation, the old is gone and the new has come! How much he must have understood the true meaning of this, and how little do we. Being set free in Jesus means we are a different person, our identity has changed, and our eternal fate is reversed.
Paul still lived with the memories of his past and I'm sure could hear the screams of those who he had executed, but His grace is sufficient and the chief of all sinners found confidence in his salvation. We carry the sins from our past life in our memories, but praise God that person before is not who the person is now.