Suspicions have been circulating about counterfeit Lee Ufan paintings being distributed in South Korea’s growing art market. Recent reports reveal that 12 of the appraised paintings are believed to be counterfeits. If confirmed, police believe that the cost of these fakes could amount to millions of dollars.

According to the Korea Herald, the inquiry started in early January of this year. The Galleries Association of Korea, an organization officially registered by the ministry of culture and information in 1979, enlisted the help of police to determine the authenticity of a certificate for Ufan’s From Point No. 780217, which sold this past December at Korea’s second-biggest auction house K-Auction for ₩400 million ($407,000).

After the Seoul Metropolitan Police Agency confirmed that the certificate was forged, they launched a full investigation into a host of Ufan’s paintings.

Choi Myung-yoon, director of the International Art and Science Institute, told the Korea Herald that “the canvases were artificially worn out and the frames colored to look old.” The paintings will be processed by the National Forensic Service for a final appraisal.

Ufan, who held a solo exhibition with Pace Gallery in New York last year, has seen his series of paintings from the 1970s fetch high sums at auction. According to the artnet Price Database, Ufan’s 1977 painting From Point fetched the highest price paid for a Ufan work at auction. It sold for $2.2 million in 2012 at Seoul Auction.

The artist released a statement this month announcing his intention to cooperate with authorities in the investigation.