Why Did the Roman Soldier Stab Jesus with His Spear?

“Why did the Roman soldier stab Jesus with a spear when scripture clearly states he was aware that Jesus was already dead?”
The account of Jesus’ is being stabbed on the cross by a Roman Soldier is found only in the Gospel of John 19.31-34: “Now it was the day of Preparation, and the next day was to be a special Sabbath. Because the Jews did not want the bodies left on the crosses during the Sabbath, they asked Pilate to have the legs broken and the bodies taken down. The soldiers therefore came and broke the legs of the first man who had been crucified with Jesus, and then those of the other. But when they came to Jesus and found that he was already dead, they did not break his legs. Instead, one of the soldiers pierced Jesus’ side with a spear, bringing a sudden flow of blood and water.”
John’s report of Jesus being stabbed on the cross is apparently the earliest attempt to verify Jesus’ death. There is no Biblical record of the name of the soldier who stabbed Jesus however, he was called Longinus, and in other versions he is called Casca. But these are only traditional - there is no proof and supposedly he was blind (why they had a blind Roman soldier remains to be seen). He is said to have stabbed Jesus and the blood that flowed from the body down the shaft of the spear of destiny cured his blindness and made a believer out of him.
In all the gospel accounts we read of surprise by the Romans that Jesus died so quickly on the cross. It is not surprising, then, that Pilate found it difficult to believe that Jesus had died so soon (Mark 15:44, 45). Crucifixion was common form of execution in the ancient world, mainly by the Carthaginians, Persians, Seleucids, and of course the Romans who used it until the fourth century, when Emperor Constantine eradicated it.
The usual crucifixion began with the victim being flogged and severely beaten. He was then forced to carry or drag the crossbeam of the cross to the place of execution and then nailed to the crossbeam which was then raised up and attached to the post about 10 to 12 feet (3 or 4 meters) off the ground. The feet were then nailed to the post. The legs were then often broken with an iron bar.
According to medical historians, The death of the victim, depending upon age and physical condition, would usually be the result of heart failure, suffocation or exhaustion - but rarely soon. In some cases, it could take days. In any event, the death could be hastened along by breaking the victim’s legs which initiated death by asphyxiation, since the victim wouldn’t be able to use his legs to push him up to get a breath of air. But Jesus’ death took less than six hours, and that without breaking his legs. A peculiar phenomenon of the day, as seen by the Romans’ reactions. And such an exception gave rise to those who doubted the veracity of Jesus’ death.
So, John had a vested interest in demonstrating that Jesus had actually died and the stabbing served to show this.
According to his superiors orders, the soldier who heard Jesus “breathe his last” (Mark 15.37; Luke 23.46) thrust his spear which was to verify that the report was accurate. when “blood and water” flowed out and as the bleeding stopped, it was clear the death sentence had been carried out. Throughout the Bible, Jesus Christ is referred to as "The Lamb of God", which is a direct reference to the slaying of the Passover lamb that was always done by its shed blood, from someone actually killing it (Exodus 12:6-7). It was not to be strangled (i.e. suffocated, as happened to crucifixion victims after their legs were broken - hanging from the arms alone eventually causes suffocation from the person unable to inhale because the full body weight would then have to be drawn upward with the chest muscles). It is also very interesting to note that none of the lamb's bones were to be broken (Numbers 9:12), something that was not done to the Christ.
It took nearly 1,800 years before we would know why Jesus died in six hours, when the norm was 36. In 1805 Dr. Gruner wrote in A Commentary on the Death of Jesus that Jesus had died of a ruptured heart muscle. In 1847 Dr. Stroud of London corroborated Gruner’s assertions, when he released his own report based on numerous post mortem examinations that claimed Jesus had not died directly from the crucifixion, but from a “laceration or rupture of the heart.”
That a Roman soldier stabbed Jesus with a spear, whether to verify or to vilify and it became clear that Jesus had died. And somehow, it seems fitting to know that Jesus died not because he was exhausted and weakened, but because he was heart broken. He died with a ruptured heart on the Cross, but not because of it.