Since it was the day of Preparation, in order to prevent the bodies from remaining on the cross on the sabbath (for that sabbath was a high day), the Jews asked Pilate that their legs be broken, and that they might be taken away. So the soldiers came and broke the legs of the first, and of the other who had been crucified with him; but when they came to Jesus and saw that he was already dead, they did not break his legs. But one of the soldiers pierced his side with a spear, and at once there came out blood and water....For these things took place that the scripture might be fulfilled, "Not a bone of him shall be broken." And again another scripture says, "They shall look on him whom they have pierced." John 19:31-37, RSV.
One male disciple did have the courage to stay with Jesus at the cross. It was the same disciple who had the "guts" to enter the courtyard of the high priest on the evening of Jesus' first trial. No wonder that John had a reputation as the disciple whom Jesus loved. He had the courage to stick with Him even though the authorities knew him to be one of Jesus' inner circle.
With those facts in mind, it is not surprising that John has something to report in his Gospel that the other three were apparently unaware of. He certifies the truth of what he has to say by pointing out that he was an eyewitness.
The first of the events he reports is the breaking of the legs of the criminals. Whereas the Romans would let a person hang suffering on a cross for days and then throw the body out for scavengers to eat, Jewish custom was much more merciful. The book of Deuteronomy stipulates that "if a man has committed a crime punishable by death and he is put to death, and you hang him on a tree, his body shall not remain all night upon the tree, but you shall bury him the same day" (Deut. 21:22, 23, RSV).
Thus it was not an accident that the Jewish leaders requested that the crucified men be removed from their crosses. But in this case it was even more important, since the next day was to be a high Sabbath when both the weekly Sabbath and the Passover day coincided.
The grim method of dispatching criminals still alive was to smash their limbs with a mallet until they died, but Jesus was already dead.
To make sure of His death a soldier speared Him in the chest. The result was a stream of blood and water. Now, dead people don't normally bleed. But it has been suggested that in cases of a ruptured heart the blood in the heart mixes with the fluid in the pericardium, which surrounds the heart. If that was the case, the spear's first thrust hit that sack of fluid, indicating that Jesus had not died from His physical injuries but from a broken heart as He bore the sins of the world.