The examination of an ancient "portal to the underworld" that has perplexed archaeologists has finally ended, officials say.

The Mexican artifact, called the Olmec Cave Mask, was stolen from the Chalcatzingo archaeological site in Mexico's Central Highlands in the 1960s. Smugglers broke the millennia-old mask into several pieces and circulated them around several museums and private collections before the full artifact was finally given back to Mexico in 2023.

The ancient artifact was crafted between 800 and 400 B.C. In an August 2023 press release from the Manhattan District Attorney's Office, officials said that the piece is said to resemble "the ancient Olmec jaguar god Tepēyōllōtl."

"[The god is] depicted as a feline with large oval eyes, flaring nostrils, and a gaping mouth," the press release describes. "Representing of the passage to the afterworld, the hulking Olmec Cave Mask guarded the entrance to a ceremonial cave at the archaeological site Chalcatzingo, Mexico."

CARVINGS ON ANCIENT STONE DISCOVERY LEAVE EXPERTS IN AWE

Split image of cave masks

The Olmec Cave Mask was stolen in the 1960s and returned last year, officials say. (National Institute of Anthropology and History (INAH) / Manhattan District Attorney’s Office)

In a May 30 press release, Mexico's National Institute of Anthropology and History (INAH) announced that the examination of the piece was reaching its end. The artifact will "return in the best possible state of conservation to its home, Jantetelco, in Morelos." 

Historians worked diligently to clean the piece and remove dust from the ancient artifact. In a press release translated from Spanish to English, the INAH explained that some parts of the mask date back 2,700 years, while others are more modern.

ANCIENT TREASURE AMONG 1,650-YEAR-OLD OBJECTS UNEARTHED IN ISRAEL

"Some elements that make it up are original, but others, such as a metal structure based on bolts, cement reinforcements and replacements of missing and shaped elements, they were added to give it stability again, although the techniques and materials were not the most suitable," the statement explained. "We observe this through x-rays, but with a partial reading, given that X-rays do not penetrate enough due to the composition and structure of the stone."

Man cleaning ancient mask

Officials worked diligently to clean dirt and other debris from the ancient artifact. (National Institute of Anthropology and History (INAH))

In May 2023, the Manhattan District Attorney's Office also explained that it took many years to seize the artifact, and required the work of several agencies.

CLICK HERE TO SIGN UP FOR OUR LIFESTYLE NEWSLETTER

"The return of the Olmec Cave Mask marked the conclusion of a complex, multi-year investigation conducted by the Office’s Antiquities Trafficking Unit with Homeland Security Investigations-New York and the unwavering support of Jorge Islas Lopez, Consul General of Mexico in New York," the office said. "Through the exceptional cooperation and assistance of Mexican Consul General Islas, the Olmec Cave Mask was seized in May and returned to Mexico City in July"

Manhattan District Attorney Alvin L. Bragg, Jr. called the artifact a "rare window into the past of Olmec society."

CLICK HERE TO GET THE FOX NEWS APP

Wide image of restored cave mask

The "portal to the underworld" depicts an ancient god called Tepēyōllōtl. (National Institute of Anthropology and History (INAH))

"Like many other looted antiquities, the Olmec Cave Mask was broken into several different pieces to make the smuggling process simpler," Bragg described. "After being sent to different museums and private collections across the United States for nearly 60 years, the Cave Mask can finally return to sit with the rest of its companion monuments."

For more Lifestyle articles, visit www.foxnews.com/lifestyle.