Judas Iscariot committed suicide when he realized the evil that he had done.
Matthew 27:3-5 (KJV)
3 Then Judas, which had betrayed him, when he saw that he was condemned, repented himself, and brought again the thirty pieces of silver to the chief priests and elders,
4 Saying, I have sinned in that I have betrayed the innocent blood. And they said, What is that to us? see thou to that.
5 And he cast down the pieces of silver in the temple, and departed, and went and hanged himself.
The passage in Matthew shows that Judas hanged himself, but Acts 1 says something else:
Acts 1:18-19 (KJV)
18 Now this man purchased a field with the reward of iniquity; and falling headlong, he burst asunder in the midst, and all his bowels gushed out.
19 And it was known unto all the dwellers at Jerusalem; insomuch as that field is called in their proper tongue, Aceldama, that is to say, The field of blood.
Are these two passages contradictory? How did Judas die?
