Authorities with the FBI's Art Crime Team visited Rohanna's home in January after reviewing surveillance footage from the night of an "ugly sweater" Christmas party at the museum on December 21.
The museum did not realize the finger was missing until weeks later, on January 8.
Security cameras show Rohana putting his hand on the left hand of the statue, and then appearing to break something off from its left hand and put it in his pocket before leaving the room, according to an arrest affidavit.
Rohana has now been charged with theft and concealment of a major artwork and Chinese authorities are demanding the book be thrown at him.
Chinese officials are calling for the "exemplary punishment" of an American student who damaged a priceless 2,200-year-old statue.
The Franklin's loan exhibit, through March 4, features a rare collection of 10 life-size clay warriors discovered at the burial complex of China's First Emperor Qin Shihuangdi, as well as significant artifacts from the site.
In recent days, a pair of Chinese officials lashed out at The Franklin Institute and issued strong words to USA prosecutors, beginning with a statement in the Communist-leaning Beijing Youth Daily, translated by The New York Times.More news: Hockey's Inclusion Message Comes Up Short As Racist Fans Taunt Black Player
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Wu added to China's CCTV that a pair of experts were headed to the City of Brotherly Love to examine the statue - and hopefully restore the thumb.
The stolen thumb was found broken when this terracotta warrior was excavated, but the fracture had been repaired before the statue went on exhibition in the United States, the centre said, and the missing thumb was snapped from the exact repaired place.
One of the famous terracotta warriors lost a finger in the incident. As a result of this incident, we have thoroughly reviewed our security protocol and procedures and have taken appropriate action where needed.
Another group of 10 terracotta warriors are now on display at the World Museum in Liverpool.
Chinese social media users were surprised the statues loaned out to the institute were kept less securely than those at museums back home.