Before excavation began, Dr. Victor Manuel Velasco, from UNAM Institute of Geophysics, determined with the help of ground penetrating radar (GPR) the approximate length of the tunnel and the presence of internal chambers.

Laser scanner has also been used to perform three dimensional register. The high resolution devise is property of the INAH National Coordination of Historical Monuments (CNMH).

Only a couple of weeks ago, the entrance of the tunnel was located at the expected place. A small opening was made and the scanner captured the first images, 37 meters into the passage.

"The complete process might take another 2 months of work, we must continue exploration with the same system used until now to avoid loosing important information that will allow us knowing activities conducted there by Teotihuacán people hundreds of years ago and why they decided to close it", mentioned Gómez Chávez.

200 tons of soil and debris have been removed to present. Nearly 60,000 fragments of artifacts have been recovered.

Ángel Mora, from the CNMH Technological Support Unit, and engineer Juan Carlos García, scanner operator, mentioned that when introducing the laser only a 37-meter length was registered. Mora declared this indicates that "the beam bumped into something, maybe rocks, a landside, or a change of level".

Sergio Gomez reported that it has not yet been precisely determined the time of construction of the tunnel, however one has a better idea of when it was closed by the people from Teotihuacán. "Several indications suggest that access to the underground passage was closed between 200 and 250 AD, probably after depositing something inside. One of the hypotheses postulate that, within the large chamber detected by the GPR, we could locate the remains of important people in the city."

The investigations have led to know with certainty that this tunnel was made prior to the construction of the Temple of the Feathered Serpent and The Citadel. The tunnel is contemporary with a large architectural structure, which could be a ball game court, according to the form of the ground, said the archaeologist.

Unfortunately, the INAH researcher said, when the tunnel was closed, large stones were thrown which blocked access, and the court was also destroyed and razed by the people of Teotihuacán, which make the work more difficult, because only small remnants remain, thus the investigations have to be continued with great care.

"Locating the entrance to the tunnel fulfills one of the most important objectives of the Project Tlalocan, to precisely confirm that the main entrance was located in the exact spot where the excavation is planned. We must continue the excavation of the vertical shaft until it reaches the floor level to thereby start explorations of the tunnel towards the East." According to the hypothesis about the meaning and symbolism of the tunnel, archaeologist Sergio Gomez, said the tunnel had to be linked to concepts related to the underworld, hence it is possible that in this place were carried out initiation rituals and the divine investiture of Teotihuacán rulers, since the power was acquired in these sacred spaces.

Also, it is known that rulers were buried in the holiest places. "For a long time local and foreign archaeologists have attempted to locate the graves of the rulers of the ancient city, but the search has been fruitless."

"That's why every day our expectations are increasing, as there are many chances that they are sitting inside a large tomb or offering. However, it is not something we are obsessed with, the discovery and systematic exploration of the tunnel is something of great significance for archaeological research and a unique opportunity to approach the cosmogonic and religious thought of ancient Teotihuacán."

At the moment the excavation have permitted to recuperate thousands of small ornaments, made of shell, jade from Guatemala, serpentine, slate and obsidian, thrown by the people from Teotihuacán as offerings at the moment of closing the entrance. Several parts of a frieze that may have decorated a building prior to the Temple of the Feathered Serpent, and that was dismantled, have been found as well.

"It is possible," concluded Sergio Gómez, "that the tunnel discovered would have been the most important and sacred element around which the first constructions were undertaken on this site about 100 B.C., and where later on The Citadel was erected, which was the magnificent stage where rituals associated with the myths of creation and the beginning of the mythic time must have been performed."