Jesus spent a total of six hours on the cross (Mark 15:25, Mark 15:34). Presumably most criminals took longer than six hours to die. Jesus had been flogged to such an extent that he was not strong enough to carry his own cross (Mark 15:15–21). He was thus very weak even before he was crucified. Pilate would not have known this. Therefore, Pilate has the centurion come in order to confirm that Jesus really is dead. He doesn’t want to allow Jesus’ body to be taken down from the cross if there is a chance that he is still alive. It would be embarrassing if someone survived a Roman crucifixion and lived to tell the tale.
44 Pilate was surprised to hear that he should have already died. And summoning the centurion, he asked him whether he was already dead.