Tonight I found the answer in a verse I hadn't really noticed before and it made me happy. Alma 49:30 says:
"Yea, and there was continual peace among them, and exceedingly great prosperity in the church because of their heed and diligence which they gave unto the word of God, which was delcared unto them by Helaman, and Shiblon, and Corianton, and Ammon and his brethern, yea, and by all those who had been ordained by the holy order of God, being baptized unto repentance, and send forth to preach among the people."
There was my answer. Corianton must have repented! It is encouraging to know that even if a person commits a serious sin, they can turn turn their lives around and again be useful servants of the Lord. It's all part of the atonement and the miracle of forgiveness.