A work of the 18th-century Joseon painter Sin Yun-bok has been reported missing and authorities are seeking tips, according to the Korea Heritage Service on Monday.

The government agency responsible for protecting such works said the Hooam Mirae Institute, a private group that held the work, contacted the agency for help locating the missing work on June 10 after police turned down its complaint citing a lack of evidence.

The Hooam Mirae Institute, which suspects an insider of the theft it believes took place between December 2019 and January 2020, reached out to police in May 2021. Police said the institute’s evidence was circumstantial, meaning they could not open a probe because there was no identifiable suspect.

In May, a Hooam Mirae Institute official met with officials from the Korea Heritage Service, communicating theft concerns on the sidelines of an event held to mark the agency’s overhaul, before formally updating the agency on the police complaint last week.

Why it took the Hoam Mirae Institute at least three years to report the missing work to the KHS remains unclear. The institute’s landline was out of service Monday and it could not be reached for comment.

Raising awareness of the missing work is the best that the government can do at the moment, said a KHS official with direct knowledge of the agency protocol for handling reports on missing historic works.

“We’ve already put out a notice detailing the missing painting and are looking at antique distribution channels,” the official said, adding antiques dealers, too, are aware of the incident.

Drawn in 1811, the painting depicting a historical event and figures was returned to Korea from Japan in 2008 after 197 years. The painting is one of the works exchanged by a Joseon diplomatic delegation and Japan, according to the National Palace Museum of Korea, which exhibited the work during its 2015 exhibition on the delegation.

The fact that the painting is not a recognized heritage renders tracing ownership harder, the KHS official said. The agency distinguishes old works recognized by the government and those without such designation. By law, the agency is compelled to extend protection to works not on the government’s priority watch list.