After the unexpected death of Miguel Ángel Fernández in 1945, Ruz Lhuillier took charge of the INAH's investigations at Palenque. While he served as the INAH's southern Director of Pre-Hispanic Monuments, Ruz Lhuillier excavated much of the city and restored and conserved such edifices as the Palace. In 1948, he discovered the entrance to the tomb of the Maya ruler, K'inich Janaab' Pakal, hidden beneath the Temple of the Inscriptions. After four seasons of clearing the rubble-filled stairway, he found Pakal's sarcophagus and body. Ruz Lhuillier's team also found the Tablet of the Palace, which served as the back to a throne, and the Tablet of the Slaves which depicts a "cahal" amid bound captives. Ruz Lhuillier continued working at the site until 1958.