Let us remember for example our father among the saints, the holy Abba Moses the Strong, who was himself a murderer and robber before his conversion and monastic vows. There is no reason to think that what God accepted of St. Moses' repentance in the 4th century could not be a comfort for a man in similar circumstances now.
Through the prayers of our Father, St. Moses the Strong, Lord comfort and forgive this man all of his sins which he has brought before You in true repentance. Lord have mercy.