Whoever put him in that cave...or said he had died or took him off the cross. I don’t know exactly who. How did they determine he was lifeless and actually dead? Just wondering. You know how they used to bury people alive all the time in the old days.... not knowing their heart was still beating.
Christ was crucified by the Romans who knew well how to kill using that method. Being nailed on a cross meant the method of death was suffocation. The weight of the body restricted the ability to breath. The victim had to stand pushing against the nails through the ankles to free the pressure on the diaphragm to breath. So the victim would be in agony going back and forth between the nails through the wrists/palms and the nails through the ankles/feet.
If it went on too long, because the Romans grew bored, they reached up and broke the legs of the victims causing them to hang by the wrists and suffocate. In Christ's case they did not break is legs, but pierced his side with a spear.
These were professionals. They knew he was dead, because they did it all the time. This was just another day in the week for them. The crucifixion wasn't unique to the Romans, this was just another work day for them. The week before they were crucifying people and the next week they were doing it too.
Joseph had to claim the body from the Romans. Christ was clearly dead, as were the two thieves with him.
Cvengr states it pretty clearly. The Romans were kind of sticklers on that sort of thing.