Police in Hong Kong have made arrests in connection with a potential HK$4 billion ($645 million) art heist that took place last month. Authorities say it could be the costliest burglary in the region’s history. 

Among the items stolen from the apartment of private collector Fu Chunxiao, who was in mainland China at the time of the incident, were a collection of 10 bronze coins, more than 24,000 stamps, and seven calligraphy scrolls supposedly written by Mao Zedong. The largest and most valuable piece in the bunch, a nine-foot-long Mao scroll, is estimated to be worth HK$2.3 billion ($300 million), according to its owner. It is also one of the only stolen objects to have been recovered by police so far.

The scroll was found in the apartment of a buyer who reportedly purchased the object from the robbers for HK$500 ($65)—before cutting it in half for ease of display. 

“He found the calligraphy piece too long and difficult to display for viewers, so he cut it in two,” Hong Kong police superintendent, Ho Chun-tung, said in a press conference this week. “Whether he knows the authenticity and value of the calligraphy is something we have to continue investigating.” 

The scroll’s buyer was arrested just days after the heist, but he has since been released. Police do not believe he was involved in the theft. 

Police show a picture of stolen antique stamps during the press conference in Hong Kong. Photo: Isaac Lawrence/AFP via Getty Images.

“It was heartbreaking to see it be torn into two pieces,” Fu told the South China Morning Post. “It will definitely affect its value, but the impact remains to be seen.”

Fu, a renowned collector of revolution-era Chinese art and artifacts, says he intended to donate the scroll to an institution before the robbery. “I have not made a decision as to how to deal with it, [and won’t] until I get it back,” he added.

The burglary took place on September 10 and involved three men who left the scene in a taxi, according to the superintendent. Later on, the driver of the cab went to local police with information about the incident, which led to the latest break in the case. 

This week, Hong Kong police arrested two new suspects: a 44-year-old man identified only as Wu, who has since been charged with burglary, and a 47-year-old accomplice who has been charged for harboring a criminal. Authorities did not recover any of the stolen objects upon raiding the homes of the two men.

Police are still on the hunt for two additional suspects identified by the taxi driver.