Given that many burial places have actually been found in the Kidron and Ben Hinnom valleys around the Old City it was not a surprise to find this burial cavern. Inside were discovered 12 ossuaries, 6 scattered about suggesting that the cave had been robbed in antiquity however 6 in their original places. Zvi Greenhut, the IAA archaeologist called to the site, recognized it as a Jewish burial cave from the Second Temple period. At this time, burial for those who can afford a family tomb, the body was laid out in a recess chiselled in the wall of the cavern and shut off. A year later, after the flesh had actually decomposed, the family members came back, opened the loculus and gathered up the bones and transferred them in a cavern with earlier bones.
That’s the explanation of the expression in the Bible “to be gathered up with his forefathers” and why it is a custom to revisit the grave after a year. Later it ended up being customary to put the bones in an unique limestone box and to write the name of the deceased on the outside– this coincided with the increase in belief of a physical resurrection at the End of Days.