According to the investigation spearheaded by the FBI, last year, during the Ugly Sweater Party hosted by the Franklin Institute in Philadelphia, 24-year-old Michael Rohana, a U.S. partygoer, somehow managed to slip off during the party and break into the museum's terracotta soldier exhibition.
According to an arrest affidavit filed Friday, 24-year-old Michael Rohana was attending an Ugly Sweater Party at the Franklin Institute December 21 when he entered the "Terracotta Warriors of the First Emperor" exhibit.
Rohana used a mobile phone as a flashlight and took a selfie with one of the warriors, China's state-run Xinhua news agency quoted the Federal Bureau of Investigation as saying.
Although the man is now booked into county jail, the Chinese authorities are demanding compensation for the damage and asked that the perpetrator be severely punished for his deed.
"The terracotta warriors are national treasures of our country", the official, who had not been named, said.
A museum spokeswoman says the statue will be repaired.
She said in a statement: "This was a deplorable act, and we share in the condemnation of this crime as expressed by our partners at the Shaanxi Cultural Heritage Promotion Center". He is now accused of theft of an artwork from a museum, concealment of the artwork and interstate transportation of stolen property, according to The New York Times.
He broke the thumb off the $4.5 million statue during the party after taking a selfie with the artifact, court documents allege.
The centre also said it was seeking initiation of a compensation procedure.
The broken-off thumb wasn't reported missing until January 8, at which point the FBI's Art Crime Team was contacted.
The warrior was one of 10 statutes which were loaned to the Philadelphia museum last September for the Terracotta Warriors of the First Emperor exhibition.
The Franklin Institute said in a statement that a security contractor failed to follow "standard closing procedures" on the night Rohana took the finger, behavior the museum called "deplorable". The terracota army has since become one of China's greatest tourist attractions. The special exhibit will run through March 4th.
Another group of 10 terracotta warriors are on display at the World Museum in the British city of Liverpool, where they will remain until October.