Exact dates are not known.
According to the Gospel of John (13:18), Jesus chose Judas Iscariot as one of his Twelve Apostles knowing that Judas would betray him. Accordingly, it is for his betrayal of Jesus, in return for 30 pieces of silver, that Judas Iscariot is known. He died directly following the betrayal, either by hanging himself or by leaping to his death (the accounts in Matthew and Acts differ).
Preparation and Calling
Nothing is known of Judas’ background prior to his calling as one of Jesus’ select Twelve, other than that he came from a village in southern Judea named Kerioth.
Interaction with God
The Apostle John claimed that Judas was a thief. He sold his Savior out to the Jewish authorities for 30 pieces of silver, but we cannot determine his motives for doing so from the scriptural record.
Testimony of Christ
Living with the Prophet
LDS Bible Dictionary
Oxford Companion to the Bible, edited by Bruce M. Metzger and Michael D. Coogan