An obscure group seeking to overthrow North Korean leader Kim Jong Un has taken responsibility for a raid on North Korea’s embassy in Madrid last month and said it shared information seized during the raid with the FBI, The Washington Post reports. In a Tuesday statement, the group, Free Joseon, claimed the information they gathered had “enormous potential value” and said the FBI had requested they voluntarily share the information. In the raid, members of the group reportedly tied up staff and stole computers and other items. A Spanish judge—who lifted a secrecy order on the case Tuesday—said “an American, a Mexican, and a South Korean” from the 10-member group had carried out the raid. The judge, Jose de la Mata, also reportedly concluded one of the men in the “criminal organization” shared some of the stolen information with the FBI. The Post reports De La Mata believes the men fled to the U.S., and said he intends to request their extradition so they can face up to 28 years in prison.

When asked if the group shared information with the FBI, the bureau said it “enjoys a strong working relationship with our Spanish law enforcement partners that centers on information-sharing and regular cooperation around matters of mutual assistance,” the Post says. The group claims it has evidence “verifying our account.” The group also claimed the FBI appeared to break “mutually agreed terms of confidentiality,” which puts those who were involved in the Madrid raid in danger.