Rescuers concluded that it would be too dangerous to attempt to retrieve his body; the landowner and Jones’ family came to an agreement that the cave would be permanently closed, with the body sealed inside, as a memorial to Jones. Explosives were used to collapse the ceiling close to Jones’ body, and the entrance hole was filled with concrete to prevent further access.
From the Wikipedia article:
This is how the Nutty Putty Cave became the Nutty Putty Grave.