Was Jesus dead before or after the spear to the side? I’ve heard both explanations.
According to the Gospel of John, Jesus had already died:
When Jesus had taken the wine, he said, “It is finished.”And bowing his head, he handed over the spirit. . . . So the soldiers came and broke the legs of the first and then of the other one who was crucified with Jesus. But when they came to Jesus and saw that he was already dead, they did not break his legs, but one soldier thrust his lance into his side, and immediately blood and water flowed out (John 19:30, 32-34).
Some have argued that the flowing of blood and water from Jesus' side is proof that he did not die until pierced with the lance. However, if the author of the Gospel was making that point, it would run contrary to the explicit theology he had already set forth in the Gospel.
The Gospel of John makes quite clear that Jesus was not merely a victim of social violence or injustice but that Jesus willingly gave of himself (John 10:18, 19:11, 19:17). Therefore, the Gospel makes clear that Jesus had already died and freely handed over his spirit prior to the piercing of the lance.