The 1891 and 1895 expeditions of the Peabody Museum of Harvard University were the first to investigate the stairway. Tatiana Proskouriakoff writes: "When John G. Owens of the Peabody Museum first began his excavations on the stairway, little was to be seen on the surface but a mass of fallen sculpture and a section comprising fifteen consecutive steps, which appeared to be in position.
After digging was begun, however, it became clear that this series of steps had slipped downward for a considerable distance, as if it had been dislodged by the sudden shock of an earthquake, and that, as found, it actually overlapped the base of the stairway, which still remained intact beneath it. This extraordinary accident was made possible by the steepness of the stairway, a very common trait of such Maya structures, in which the treads of the steps actually measure less than the risers, reversing the proportion usual in modern design.
Mr. Owens died at Copán of one of those malignant fevers that are a dreaded hazard to all travelers in Middle America, but his work was continued by his former assistant, who later published a detailed report. The repair of the stairway was one of the chief project of the co-operative undertaking of the government of Honduras and the Carnegie Institution of Washington, and was completed in 1942. "
Tatiana Proskouriakoff, An Album of Maya Architecture, p. 35-6